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/* Copyright (C) 2004 MySQL AB

  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
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  the Free Software Foundation; version 2 of the License.
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  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

/*

  MySQL Federated Storage Engine

  ha_federated.cc - MySQL Federated Storage Engine
  Patrick Galbraith and Brian Aker, 2004

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  This is a handler which uses a foreign database as the data file, as
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  opposed to a handler like MyISAM, which uses .MYD files locally.

  How this handler works
  ----------------------------------
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  Normal database files are local and as such: You create a table called
  'users', a file such as 'users.MYD' is created. A handler reads, inserts,
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  deletes, updates data in this file. The data is stored in particular format,
  so to read, that data has to be parsed into fields, to write, fields have to
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  be stored in this format to write to this data file.
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  With MySQL Federated storage engine, there will be no local files
  for each table's data (such as .MYD). A foreign database will store
  the data that would normally be in this file. This will necessitate
  the use of MySQL client API to read, delete, update, insert this
  data. The data will have to be retrieve via an SQL call "SELECT *
  FROM users". Then, to read this data, it will have to be retrieved
  via mysql_fetch_row one row at a time, then converted from the
  column in this select into the format that the handler expects.
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  The create table will simply create the .frm file, and within the
  "CREATE TABLE" SQL, there SHALL be any of the following :
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  comment=scheme://username:password@hostname:port/database/tablename
  comment=scheme://username@hostname/database/tablename
  comment=scheme://username:password@hostname/database/tablename
  comment=scheme://username:password@hostname/database/tablename

  An example would be:

  comment=mysql://username:password@hostname:port/database/tablename

  ***IMPORTANT***

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  This is a first release, conceptual release
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  Only 'mysql://' is supported at this release.


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  This comment connection string is necessary for the handler to be
  able to connect to the foreign server.
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  The basic flow is this:

  SQL calls issues locally ->
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  mysql handler API (data in handler format) ->
  mysql client API (data converted to SQL calls) ->
  foreign database -> mysql client API ->
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  convert result sets (if any) to handler format ->
  handler API -> results or rows affected to local

  What this handler does and doesn't support
  ------------------------------------------
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  * Tables MUST be created on the foreign server prior to any action on those
    tables via the handler, first version. IMPORTANT: IF you MUST use the
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    federated storage engine type on the REMOTE end, MAKE SURE [ :) ] That
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    the table you connect to IS NOT a table pointing BACK to your ORIGNAL
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    table! You know  and have heard the screaching of audio feedback? You
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    know putting two mirror in front of each other how the reflection
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    continues for eternity? Well, need I say more?!
  * There will not be support for transactions.
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  * There is no way for the handler to know if the foreign database or table
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    has changed. The reason for this is that this database has to work like a
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    data file that would never be written to by anything other than the
    database. The integrity of the data in the local table could be breached
    if there was any change to the foreign database.
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  * Support for SELECT, INSERT, UPDATE , DELETE, indexes.
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  * No ALTER TABLE, DROP TABLE or any other Data Definition Language calls.
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  * Prepared statements will not be used in the first implementation, it
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    remains to to be seen whether the limited subset of the client API for the
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    server supports this.
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  * This uses SELECT, INSERT, UPDATE, DELETE and not HANDLER for its
    implementation.
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  * This will not work with the query cache.
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   Method calls

   A two column table, with one record:

   (SELECT)

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   "SELECT * FROM foo"
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    ha_federated::info
    ha_federated::scan_time:
    ha_federated::rnd_init: share->select_query SELECT * FROM foo
    ha_federated::extra

    <for every row of data retrieved>
    ha_federated::rnd_next
    ha_federated::convert_row_to_internal_format
    ha_federated::rnd_next
    </for every row of data retrieved>

    ha_federated::rnd_end
    ha_federated::extra
    ha_federated::reset

    (INSERT)

    "INSERT INTO foo (id, ts) VALUES (2, now());"

    ha_federated::write_row

    ha_federated::reset

    (UPDATE)

    "UPDATE foo SET ts = now() WHERE id = 1;"

    ha_federated::index_init
    ha_federated::index_read
    ha_federated::index_read_idx
    ha_federated::rnd_next
    ha_federated::convert_row_to_internal_format
    ha_federated::update_row
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    ha_federated::extra
    ha_federated::extra
    ha_federated::extra
    ha_federated::external_lock
    ha_federated::reset


    How do I use this handler?
    --------------------------
    First of all, you need to build this storage engine:
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      ./configure --with-federated-storage-engine
      make

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    Next, to use this handler, it's very simple. You must
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    have two databases running, either both on the same host, or
    on different hosts.

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    One the server that will be connecting to the foreign
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    host (client), you create your table as such:

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    CREATE TABLE test_table (
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      id     int(20) NOT NULL auto_increment,
      name   varchar(32) NOT NULL default '',
      other  int(20) NOT NULL default '0',
      PRIMARY KEY  (id),
      KEY name (name),
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      KEY other_key (other))
       ENGINE="FEDERATED"
       DEFAULT CHARSET=latin1
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       COMMENT='root@127.0.0.1:9306/federated/test_federated';

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   Notice the "COMMENT" and "ENGINE" field? This is where you
   respectively set the engine type, "FEDERATED" and foreign
   host information, this being the database your 'client' database
   will connect to and use as the "data file". Obviously, the foreign
   database is running on port 9306, so you want to start up your other
   database so that it is indeed on port 9306, and your federated
   database on a port other than that. In my setup, I use port 5554
   for federated, and port 5555 for the foreign database.
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   Then, on the foreign database:
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   CREATE TABLE test_table (
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     id     int(20) NOT NULL auto_increment,
     name   varchar(32) NOT NULL default '',
     other  int(20) NOT NULL default '0',
     PRIMARY KEY  (id),
     KEY name (name),
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     KEY other_key (other))
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     ENGINE="<NAME>" <-- whatever you want, or not specify
     DEFAULT CHARSET=latin1 ;

    This table is exactly the same (and must be exactly the same),
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    except that it is not using the federated handler and does
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    not need the URL.
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    How to see the handler in action
    --------------------------------

    When developing this handler, I compiled the federated database with
    debugging:

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    ./configure --with-federated-storage-engine
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    --prefix=/home/mysql/mysql-build/federated/ --with-debug

    Once compiled, I did a 'make install' (not for the purpose of installing
    the binary, but to install all the files the binary expects to see in the
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    diretory I specified in the build with --prefix,
    "/home/mysql/mysql-build/federated".

    Then, I started the foreign server:
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    /usr/local/mysql/bin/mysqld_safe
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    --user=mysql --log=/tmp/mysqld.5555.log -P 5555

    Then, I went back to the directory containing the newly compiled mysqld,
    <builddir>/sql/, started up gdb:

    gdb ./mysqld

    Then, withn the (gdb) prompt:
    (gdb) run --gdb --port=5554 --socket=/tmp/mysqld.5554 --skip-innodb --debug

    Next, I open several windows for each:

    1. Tail the debug trace: tail -f /tmp/mysqld.trace|grep ha_fed
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    2. Tail the SQL calls to the foreign database: tail -f /tmp/mysqld.5555.log
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    3. A window with a client open to the federated server on port 5554
    4. A window with a client open to the federated server on port 5555

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    I would create a table on the client to the foreign server on port
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    5555, and then to the federated server on port 5554. At this point,
    I would run whatever queries I wanted to on the federated server,
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    just always remembering that whatever changes I wanted to make on
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    the table, or if I created new tables, that I would have to do that
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    on the foreign server.

    Another thing to look for is 'show variables' to show you that you have
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    support for federated handler support:

    show variables like '%federat%'

    and:

    show storage engines;

    Both should display the federated storage handler.


    Testing
    -------

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    There is a test for MySQL Federated Storage Handler in ./mysql-test/t,
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    federatedd.test It starts both a slave and master database using
    the same setup that the replication tests use, with the exception that
    it turns off replication, and sets replication to ignore the test tables.
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    After ensuring that you actually do have support for the federated storage
    handler, numerous queries/inserts/updates/deletes are run, many derived
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    from the MyISAM tests, plus som other tests which were meant to reveal
    any issues that would be most likely to affect this handler. All tests
    should work! ;)

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    To run these tests, go into ./mysql-test (based in the directory you
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    built the server in)

    ./mysql-test-run federatedd
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    To run the test, or if you want to run the test and have debug info:

    ./mysql-test-run --debug federated

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    This will run the test in debug mode, and you can view the trace and
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    log files in the ./mysql-test/var/log directory

    ls -l mysql-test/var/log/
    -rw-r--r--  1 patg  patg        17  4 Dec 12:27 current_test
    -rw-r--r--  1 patg  patg       692  4 Dec 12:52 manager.log
    -rw-rw----  1 patg  patg     21246  4 Dec 12:51 master-bin.000001
    -rw-rw----  1 patg  patg        68  4 Dec 12:28 master-bin.index
    -rw-r--r--  1 patg  patg      1620  4 Dec 12:51 master.err
    -rw-rw----  1 patg  patg     23179  4 Dec 12:51 master.log
    -rw-rw----  1 patg  patg  16696550  4 Dec 12:51 master.trace
    -rw-r--r--  1 patg  patg         0  4 Dec 12:28 mysqltest-time
    -rw-r--r--  1 patg  patg   2024051  4 Dec 12:51 mysqltest.trace
    -rw-rw----  1 patg  patg     94992  4 Dec 12:51 slave-bin.000001
    -rw-rw----  1 patg  patg        67  4 Dec 12:28 slave-bin.index
    -rw-rw----  1 patg  patg       249  4 Dec 12:52 slave-relay-bin.000003
    -rw-rw----  1 patg  patg        73  4 Dec 12:28 slave-relay-bin.index
    -rw-r--r--  1 patg  patg      1349  4 Dec 12:51 slave.err
    -rw-rw----  1 patg  patg     96206  4 Dec 12:52 slave.log
    -rw-rw----  1 patg  patg  15706355  4 Dec 12:51 slave.trace
    -rw-r--r--  1 patg  patg         0  4 Dec 12:51 warnings

    Of course, again, you can tail the trace log:

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    tail -f mysql-test/var/log/master.trace |grep ha_fed
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    As well as the slave query log:
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    tail -f mysql-test/var/log/slave.log

    Files that comprise the test suit
    ---------------------------------
    mysql-test/t/federated.test
    mysql-test/r/federated.result
    mysql-test/r/have_federated_db.require
    mysql-test/include/have_federated_db.inc


    Other tidbits
    -------------

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    These were the files that were modified or created for this
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    Federated handler to work:

    ./configure.in
    ./sql/Makefile.am
    ./config/ac_macros/ha_federated.m4
    ./sql/handler.cc
    ./sql/mysqld.cc
    ./sql/set_var.cc
    ./sql/field.h
    ./sql/sql_string.h
    ./mysql-test/mysql-test-run(.sh)
    ./mysql-test/t/federated.test
    ./mysql-test/r/federated.result
    ./mysql-test/r/have_federated_db.require
    ./mysql-test/include/have_federated_db.inc
    ./sql/ha_federated.cc
    ./sql/ha_federated.h
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*/
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#define MYSQL_SERVER 1
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#include "mysql_priv.h"
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#include <mysql/plugin.h>

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#ifdef USE_PRAGMA_IMPLEMENTATION
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#pragma implementation                          // gcc: Class implementation
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#endif

#include "ha_federated.h"
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#include "m_string.h"
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#include <mysql/plugin.h>

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/* Variables for federated share methods */
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static HASH federated_open_tables;              // To track open tables
pthread_mutex_t federated_mutex;                // To init the hash
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/* Variables used when chopping off trailing characters */
static const uint sizeof_trailing_comma= sizeof(", ") - 1;
static const uint sizeof_trailing_closeparen= sizeof(") ") - 1;
static const uint sizeof_trailing_and= sizeof(" AND ") - 1;
static const uint sizeof_trailing_where= sizeof(" WHERE ") - 1;

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/* Static declaration for handerton */
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static handler *federated_create_handler(handlerton *hton,
                                         TABLE_SHARE *table,
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                                         MEM_ROOT *mem_root);
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static int federated_commit(handlerton *hton, THD *thd, bool all);
static int federated_rollback(handlerton *hton, THD *thd, bool all);
static int federated_db_init(void);
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/* Federated storage engine handlerton */
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static handler *federated_create_handler(handlerton *hton, 
                                         TABLE_SHARE *table,
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                                         MEM_ROOT *mem_root)
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{
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  return new (mem_root) ha_federated(hton, table);
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}


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/* Function we use in the creation of our hash to get key */
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static byte *federated_get_key(FEDERATED_SHARE *share, uint *length,
                               my_bool not_used __attribute__ ((unused)))
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{
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  *length= share->share_key_length;
  return (byte*) share->share_key;
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}

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/*
  Initialize the federated handler.

  SYNOPSIS
    federated_db_init()
    void

  RETURN
    FALSE       OK
    TRUE        Error
*/

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int federated_db_init(void *p)
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{
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  DBUG_ENTER("federated_db_init");
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  handlerton *federated_hton= (handlerton *)p;
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  federated_hton->state= SHOW_OPTION_YES;
  federated_hton->db_type= DB_TYPE_FEDERATED_DB;
  federated_hton->commit= federated_commit;
  federated_hton->rollback= federated_rollback;
  federated_hton->create= federated_create_handler;
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  federated_hton->flags= HTON_ALTER_NOT_SUPPORTED | HTON_NO_PARTITION;
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  if (pthread_mutex_init(&federated_mutex, MY_MUTEX_INIT_FAST))
    goto error;
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  if (!hash_init(&federated_open_tables, &my_charset_bin, 32, 0, 0,
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                    (hash_get_key) federated_get_key, 0, 0))
  {
    DBUG_RETURN(FALSE);
  }
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  VOID(pthread_mutex_destroy(&federated_mutex));
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error:
  DBUG_RETURN(TRUE);
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}


/*
  Release the federated handler.

  SYNOPSIS
    federated_db_end()

  RETURN
    FALSE       OK
*/

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int federated_done(void *p)
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{
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  hash_free(&federated_open_tables);
  VOID(pthread_mutex_destroy(&federated_mutex));

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  return 0;
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}

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/*
 Check (in create) whether the tables exists, and that it can be connected to

  SYNOPSIS
    check_foreign_data_source()
      share               pointer to FEDERATED share
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      table_create_flag   tells us that ::create is the caller, 
                          therefore, return CANT_CREATE_FEDERATED_TABLE
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  DESCRIPTION
    This method first checks that the connection information that parse url
    has populated into the share will be sufficient to connect to the foreign
    table, and if so, does the foreign table exist.
*/

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static int check_foreign_data_source(FEDERATED_SHARE *share,
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                                     bool table_create_flag)
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{
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  char escaped_table_name[NAME_LEN*2];
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  char query_buffer[FEDERATED_QUERY_BUFFER_SIZE];
  char error_buffer[FEDERATED_QUERY_BUFFER_SIZE];
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  uint error_code;
  String query(query_buffer, sizeof(query_buffer), &my_charset_bin);
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  MYSQL *mysql;
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  DBUG_ENTER("ha_federated::check_foreign_data_source");
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  /* Zero the length, otherwise the string will have misc chars */
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  query.length(0);

  /* error out if we can't alloc memory for mysql_init(NULL) (per Georg) */
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  if (!(mysql= mysql_init(NULL)))
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    DBUG_RETURN(HA_ERR_OUT_OF_MEM);
  /* check if we can connect */
  if (!mysql_real_connect(mysql,
                          share->hostname,
                          share->username,
                          share->password,
                          share->database,
                          share->port,
                          share->socket, 0))
  {
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    /*
      we want the correct error message, but it to return
      ER_CANT_CREATE_FEDERATED_TABLE if called by ::create
    */
    error_code= (table_create_flag ?
                 ER_CANT_CREATE_FEDERATED_TABLE :
                 ER_CONNECT_TO_FOREIGN_DATA_SOURCE);
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    my_sprintf(error_buffer,
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               (error_buffer,
                "database: '%s'  username: '%s'  hostname: '%s'",
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                share->database, share->username, share->hostname));

    my_error(ER_CONNECT_TO_FOREIGN_DATA_SOURCE, MYF(0), error_buffer);
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    goto error;
  }
  else
  {
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    int escaped_table_name_length= 0;
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    /*
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      Since we do not support transactions at this version, we can let the 
      client API silently reconnect. For future versions, we will need more 
      logic to deal with transactions
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    */
    mysql->reconnect= 1;
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    /*
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      Note: I am not using INORMATION_SCHEMA because this needs to work with 
      versions prior to 5.0
      
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      if we can connect, then make sure the table exists 
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      the query will be: SELECT * FROM `tablename` WHERE 1=0
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    */
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    query.append(STRING_WITH_LEN("SELECT * FROM `"));
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    escaped_table_name_length=
      escape_string_for_mysql(&my_charset_bin, (char*)escaped_table_name,
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                            sizeof(escaped_table_name),
                            share->table_name,
                            share->table_name_length);
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    query.append(escaped_table_name, escaped_table_name_length);
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    query.append(STRING_WITH_LEN("` WHERE 1=0"));
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    if (mysql_real_query(mysql, query.ptr(), query.length()))
    {
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      error_code= table_create_flag ?
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        ER_CANT_CREATE_FEDERATED_TABLE : ER_FOREIGN_DATA_SOURCE_DOESNT_EXIST;
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      my_sprintf(error_buffer, (error_buffer, "error: %d  '%s'",
                                mysql_errno(mysql), mysql_error(mysql)));
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      my_error(error_code, MYF(0), error_buffer);
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      goto error;
    }
  }
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  error_code=0;
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error:
    mysql_close(mysql);
    DBUG_RETURN(error_code);
}


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static int parse_url_error(FEDERATED_SHARE *share, TABLE *table, int error_num)
{
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  char buf[FEDERATED_QUERY_BUFFER_SIZE];
  int buf_len;
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  DBUG_ENTER("ha_federated parse_url_error");
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  if (share->connection_string)
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  {
    DBUG_PRINT("info",
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               ("error: parse_url. Returning error code %d \
                freeing share->connection_string %lx",
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                error_num, (long unsigned int) share->connection_string));
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    my_free((gptr) share->connection_string, MYF(0));
    share->connection_string= 0;
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  }
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  buf_len= min(table->s->connect_string.length,
               FEDERATED_QUERY_BUFFER_SIZE-1);
  strmake(buf, table->s->connect_string.str, buf_len);
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  my_error(error_num, MYF(0), buf);
  DBUG_RETURN(error_num);
}
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/*
  retrieve server object which contains server meta-data 
  from the system table given a server's name, set share
  connection parameter members
*/
int get_connection(FEDERATED_SHARE *share)
{
  int error_num= ER_FOREIGN_SERVER_DOESNT_EXIST;
  char error_buffer[FEDERATED_QUERY_BUFFER_SIZE];
  FOREIGN_SERVER *server;
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  MYSQL *mysql_conn= 0;
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  MYSQL_RES *result= 0;
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  MYSQL_ROW row= 0;
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  DBUG_ENTER("ha_federated::get_connection");

  if (!(server=
       get_server_by_name(share->connection_string)))
  {
    DBUG_PRINT("info", ("get_server_by_name returned > 0 error condition!"));
    /* need to come up with error handling */
    error_num=1;
    goto error;
  }
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  DBUG_PRINT("info", ("get_server_by_name returned server at %lx", (long unsigned int) server));
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  /*
    Most of these should never be empty strings, error handling will
    need to be implemented. Also, is this the best way to set the share
    members? Is there some allocation needed? In running this code, it works
    except there are errors in the trace file of the share being overrun 
    at the address of the share.
  */
  if (server->server_name)
    share->server_name= server->server_name;
  share->server_name_length= server->server_name_length ?
    server->server_name_length : 0;
  if (server->username)
    share->username= server->username;
  if (server->password)
    share->password= server->password;
  if (server->db)
    share->database= server->db;
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  share->port= server->port ? (ushort) server->port : MYSQL_PORT;
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  if (server->host)
    share->hostname= server->host;
  if (server->socket)
    share->socket= server->socket;
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  else if (strcmp(share->hostname, my_localhost) == 0)
    share->socket= my_strdup(MYSQL_UNIX_ADDR, MYF(0));
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  if (server->scheme)
    share->scheme= server->scheme;
  else
    share->scheme= NULL;

  DBUG_PRINT("info", ("share->username %s", share->username));
  DBUG_PRINT("info", ("share->password %s", share->password));
  DBUG_PRINT("info", ("share->hostname %s", share->hostname));
  DBUG_PRINT("info", ("share->database %s", share->database));
  DBUG_PRINT("info", ("share->port %d", share->port));
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  DBUG_PRINT("info", ("share->socket %s", share->socket));
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  DBUG_RETURN(0);

error:
  my_sprintf(error_buffer,
             (error_buffer, "server name: '%s' doesn't exist!",
              share->connection_string));
  my_error(error_num, MYF(0), error_buffer);
  DBUG_RETURN(error_num);
}
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/*
639
  Parse connection info from table->s->connect_string
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  SYNOPSIS
    parse_url()
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    share               pointer to FEDERATED share
    table               pointer to current TABLE class
    table_create_flag   determines what error to throw
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  DESCRIPTION
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    Populates the share with information about the connection
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    to the foreign database that will serve as the data source.
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    This string must be specified (currently) in the "CONNECTION" field,
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    listed in the CREATE TABLE statement.
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    This string MUST be in the format of any of these:

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    CONNECTION="scheme://username:password@hostname:port/database/table"
    CONNECTION="scheme://username@hostname/database/table"
    CONNECTION="scheme://username@hostname:port/database/table"
    CONNECTION="scheme://username:password@hostname/database/table"

    _OR_

    CONNECTION="connection name"

    
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  An Example:

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  CREATE TABLE t1 (id int(32))
    ENGINE="FEDERATED"
    CONNECTION="mysql://joe:joespass@192.168.1.111:9308/federated/testtable";

  CREATE TABLE t2 (
    id int(4) NOT NULL auto_increment,
    name varchar(32) NOT NULL,
    PRIMARY KEY(id)
    ) ENGINE="FEDERATED" CONNECTION="my_conn";
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  ***IMPORTANT***
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  Currently, the Federated Storage Engine only supports connecting to another
  MySQL Database ("scheme" of "mysql"). Connections using JDBC as well as 
  other connectors are in the planning stage.
  
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  'password' and 'port' are both optional.
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  RETURN VALUE
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    0           success
    error_num   particular error code 
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*/
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static int parse_url(FEDERATED_SHARE *share, TABLE *table,
                     uint table_create_flag)
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{
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  uint error_num= (table_create_flag ?
                   ER_FOREIGN_DATA_STRING_INVALID_CANT_CREATE :
                   ER_FOREIGN_DATA_STRING_INVALID);
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  DBUG_ENTER("ha_federated::parse_url");
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  share->port= 0;
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  share->socket= 0;
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  DBUG_PRINT("info", ("share at %lx", (long unsigned int) share));
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  DBUG_PRINT("info", ("Length: %d", table->s->connect_string.length));
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  DBUG_PRINT("info", ("String: '%.*s'", table->s->connect_string.length,
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                      table->s->connect_string.str));
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  share->connection_string= my_strndup(table->s->connect_string.str,
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                                       table->s->connect_string.length,
                                       MYF(0));

  // Add a null for later termination of table name
  share->connection_string[table->s->connect_string.length]= 0;
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  DBUG_PRINT("info",("parse_url alloced share->connection_string %lx",
                     (long unsigned int) share->connection_string));
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  DBUG_PRINT("info",("share->connection_string %s",share->connection_string));
  /* No delimiters, must be a straight connection name */
  if ( (!strchr(share->connection_string, '/')) &&
       (!strchr(share->connection_string, '@')) &&
       (!strchr(share->connection_string, ';')))
  {
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    DBUG_PRINT("info",
               ("share->connection_string %s internal format \
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                share->connection_string %lx",
                share->connection_string,
                (long unsigned int) share->connection_string));
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    share->parsed= FALSE;
    if ((error_num= get_connection(share)))
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      goto error;
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    /*
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      connection specifies everything but, resort to
      expecting remote and foreign table names to match
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    */
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    share->table_name= table->s->table_name.str;
    share->table_name_length= table->s->table_name.length;
    share->table_name[share->table_name_length]= '\0';
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  }
  else
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  {
    share->parsed= TRUE;
    // Add a null for later termination of table name
    share->connection_string[table->s->connect_string.length]= 0;
    share->scheme= share->connection_string;
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    DBUG_PRINT("info",("parse_url alloced share->scheme %lx",
                       (long unsigned int) share->scheme));
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    /*
      remove addition of null terminator and store length
      for each string  in share
    */
    if (!(share->username= strstr(share->scheme, "://")))
      goto error;
    share->scheme[share->username - share->scheme]= '\0';
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    if (strcmp(share->scheme, "mysql") != 0)
      goto error;
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    share->username+= 3;

    if (!(share->hostname= strchr(share->username, '@')))
      goto error;

    share->username[share->hostname - share->username]= '\0';
    share->hostname++;

    if ((share->password= strchr(share->username, ':')))
    {
      share->username[share->password - share->username]= '\0';
      share->password++;
      share->username= share->username;
      /* make sure there isn't an extra / or @ */
      if ((strchr(share->password, '/') || strchr(share->hostname, '@')))
        goto error;
      /*
        Found that if the string is:
user:@hostname:port/db/table
Then password is a null string, so set to NULL
    */
      if ((share->password[0] == '\0'))
        share->password= NULL;
    }
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    else
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      share->username= share->username;
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    /* make sure there isn't an extra / or @ */
    if ((strchr(share->username, '/')) || (strchr(share->hostname, '@')))
      goto error;
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    if (!(share->database= strchr(share->hostname, '/')))
      goto error;
    share->hostname[share->database - share->hostname]= '\0';
    share->database++;
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    if ((share->sport= strchr(share->hostname, ':')))
    {
      share->hostname[share->sport - share->hostname]= '\0';
      share->sport++;
      if (share->sport[0] == '\0')
        share->sport= NULL;
      else
        share->port= atoi(share->sport);
    }
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    if (!(share->table_name= strchr(share->database, '/')))
      goto error;
    share->database[share->table_name - share->database]= '\0';
    share->table_name++;
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    share->table_name_length= strlen(share->table_name);

    /* make sure there's not an extra / */
    if ((strchr(share->table_name, '/')))
      goto error;

    if (share->hostname[0] == '\0')
      share->hostname= NULL;

  }
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  if (!share->port)
  {
    if (strcmp(share->hostname, my_localhost) == 0)
      share->socket= my_strdup(MYSQL_UNIX_ADDR, MYF(0));
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    else
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      share->port= MYSQL_PORT;
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  }
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  DBUG_PRINT("info",
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             ("scheme: %s  username: %s  password: %s \
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               hostname: %s  port: %d  db: %s  tablename: %s",
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              share->scheme, share->username, share->password,
              share->hostname, share->port, share->database,
              share->table_name));
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  DBUG_RETURN(0);

error:
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  DBUG_RETURN(parse_url_error(share, table, error_num));
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}

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/*****************************************************************************
** FEDERATED tables
*****************************************************************************/

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ha_federated::ha_federated(handlerton *hton,
                           TABLE_SHARE *table_arg)
  :handler(hton, table_arg),
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  mysql(0), stored_result(0)
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{
  trx_next= 0;
}
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/*
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  Convert MySQL result set row to handler internal format

  SYNOPSIS
    convert_row_to_internal_format()
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      record    Byte pointer to record
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      row       MySQL result set row from fetchrow()
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      result	Result set to use
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  DESCRIPTION
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    This method simply iterates through a row returned via fetchrow with
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    values from a successful SELECT , and then stores each column's value
    in the field object via the field object pointer (pointing to the table's
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    array of field object pointers). This is how the handler needs the data
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    to be stored to then return results back to the user

  RETURN VALUE
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    0   After fields have had field values stored from record
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*/
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uint ha_federated::convert_row_to_internal_format(byte *record,
                                                  MYSQL_ROW row,
                                                  MYSQL_RES *result)
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{
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  ulong *lengths;
  Field **field;
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  my_bitmap_map *old_map= dbug_tmp_use_all_columns(table, table->write_set);
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  DBUG_ENTER("ha_federated::convert_row_to_internal_format");

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  lengths= mysql_fetch_lengths(result);
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  for (field= table->field; *field; field++, row++, lengths++)
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  {
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    /*
      index variable to move us through the row at the
      same iterative step as the field
    */
    my_ptrdiff_t old_ptr;
    old_ptr= (my_ptrdiff_t) (record - table->record[0]);
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    (*field)->move_field_offset(old_ptr);
    if (!*row)
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      (*field)->set_null();
    else
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    {
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      if (bitmap_is_set(table->read_set, (*field)->field_index))
      {
        (*field)->set_notnull();
        (*field)->store(*row, *lengths, &my_charset_bin);
      }
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    }
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    (*field)->move_field_offset(-old_ptr);
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  }
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  dbug_tmp_restore_column_map(table->write_set, old_map);
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  DBUG_RETURN(0);
}

static bool emit_key_part_name(String *to, KEY_PART_INFO *part)
{
  DBUG_ENTER("emit_key_part_name");
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  if (to->append(STRING_WITH_LEN("`")) ||
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      to->append(part->field->field_name) ||
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      to->append(STRING_WITH_LEN("`")))
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    DBUG_RETURN(1);                           // Out of memory
  DBUG_RETURN(0);
}

static bool emit_key_part_element(String *to, KEY_PART_INFO *part,
                                  bool needs_quotes, bool is_like,
                                  const byte *ptr, uint len)
{
  Field *field= part->field;
  DBUG_ENTER("emit_key_part_element");

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  if (needs_quotes && to->append(STRING_WITH_LEN("'")))
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    DBUG_RETURN(1);

  if (part->type == HA_KEYTYPE_BIT)
  {
    char buff[STRING_BUFFER_USUAL_SIZE], *buf= buff;

    *buf++= '0';
    *buf++= 'x';
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    buf= octet2hex(buf, (char*) ptr, len);
    if (to->append((char*) buff, (uint)(buf - buff)))
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      DBUG_RETURN(1);
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  }
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  else if (part->key_part_flag & HA_BLOB_PART)
  {
    String blob;
    uint blob_length= uint2korr(ptr);
    blob.set_quick((char*) ptr+HA_KEY_BLOB_LENGTH,
                   blob_length, &my_charset_bin);
    if (append_escaped(to, &blob))
      DBUG_RETURN(1);
  }
  else if (part->key_part_flag & HA_VAR_LENGTH_PART)
  {
    String varchar;
    uint var_length= uint2korr(ptr);
    varchar.set_quick((char*) ptr+HA_KEY_BLOB_LENGTH,
                      var_length, &my_charset_bin);
    if (append_escaped(to, &varchar))
      DBUG_RETURN(1);
  }
  else
  {
    char strbuff[MAX_FIELD_WIDTH];
    String str(strbuff, sizeof(strbuff), part->field->charset()), *res;

    res= field->val_str(&str, (char *)ptr);

    if (field->result_type() == STRING_RESULT)
    {
      if (append_escaped(to, res))
        DBUG_RETURN(1);
    }
    else if (to->append(res->ptr(), res->length()))
      DBUG_RETURN(1);
  }

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  if (is_like && to->append(STRING_WITH_LEN("%")))
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    DBUG_RETURN(1);

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  if (needs_quotes && to->append(STRING_WITH_LEN("'")))
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    DBUG_RETURN(1);
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  DBUG_RETURN(0);
}

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/*
  Create a WHERE clause based off of values in keys
  Note: This code was inspired by key_copy from key.cc

  SYNOPSIS
    create_where_from_key ()
      to          String object to store WHERE clause
      key_info    KEY struct pointer
      key         byte pointer containing key
      key_length  length of key
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      range_type  0 - no range, 1 - min range, 2 - max range
                  (see enum range_operation)
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  DESCRIPTION
    Using iteration through all the keys via a KEY_PART_INFO pointer,
    This method 'extracts' the value of each key in the byte pointer
    *key, and for each key found, constructs an appropriate WHERE clause

  RETURN VALUE
    0   After all keys have been accounted for to create the WHERE clause
    1   No keys found

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    Range flags Table per Timour:

   -----------------
   - start_key:
     * ">"  -> HA_READ_AFTER_KEY
     * ">=" -> HA_READ_KEY_OR_NEXT
     * "="  -> HA_READ_KEY_EXACT

   - end_key:
     * "<"  -> HA_READ_BEFORE_KEY
     * "<=" -> HA_READ_AFTER_KEY

   records_in_range:
   -----------------
   - start_key:
     * ">"  -> HA_READ_AFTER_KEY
     * ">=" -> HA_READ_KEY_EXACT
     * "="  -> HA_READ_KEY_EXACT

   - end_key:
     * "<"  -> HA_READ_BEFORE_KEY
     * "<=" -> HA_READ_AFTER_KEY
     * "="  -> HA_READ_AFTER_KEY
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0 HA_READ_KEY_EXACT,              Find first record else error
1 HA_READ_KEY_OR_NEXT,            Record or next record
2 HA_READ_KEY_OR_PREV,            Record or previous
3 HA_READ_AFTER_KEY,              Find next rec. after key-record
4 HA_READ_BEFORE_KEY,             Find next rec. before key-record
5 HA_READ_PREFIX,                 Key which as same prefix
6 HA_READ_PREFIX_LAST,            Last key with the same prefix
7 HA_READ_PREFIX_LAST_OR_PREV,    Last or prev key with the same prefix

Flags that I've found:

id, primary key, varchar

id = 'ccccc'
records_in_range: start_key 0 end_key 3
read_range_first: start_key 0 end_key NULL

id > 'ccccc'
records_in_range: start_key 3 end_key NULL
read_range_first: start_key 3 end_key NULL

id < 'ccccc'
records_in_range: start_key NULL end_key 4
read_range_first: start_key NULL end_key 4

id <= 'ccccc'
records_in_range: start_key NULL end_key 3
read_range_first: start_key NULL end_key 3

id >= 'ccccc'
records_in_range: start_key 0 end_key NULL
read_range_first: start_key 1 end_key NULL

id like 'cc%cc'
records_in_range: start_key 0 end_key 3
read_range_first: start_key 1 end_key 3

id > 'aaaaa' and id < 'ccccc'
records_in_range: start_key 3 end_key 4
read_range_first: start_key 3 end_key 4

id >= 'aaaaa' and id < 'ccccc';
records_in_range: start_key 0 end_key 4
read_range_first: start_key 1 end_key 4

id >= 'aaaaa' and id <= 'ccccc';
records_in_range: start_key 0 end_key 3
read_range_first: start_key 1 end_key 3

id > 'aaaaa' and id <= 'ccccc';
records_in_range: start_key 3 end_key 3
read_range_first: start_key 3 end_key 3

numeric keys:

id = 4
index_read_idx: start_key 0 end_key NULL 

id > 4
records_in_range: start_key 3 end_key NULL
read_range_first: start_key 3 end_key NULL

id >= 4
records_in_range: start_key 0 end_key NULL
read_range_first: start_key 1 end_key NULL

id < 4
records_in_range: start_key NULL end_key 4
read_range_first: start_key NULL end_key 4

id <= 4
records_in_range: start_key NULL end_key 3
read_range_first: start_key NULL end_key 3

id like 4
full table scan, select * from

id > 2 and id < 8
records_in_range: start_key 3 end_key 4
read_range_first: start_key 3 end_key 4

id >= 2 and id < 8
records_in_range: start_key 0 end_key 4
read_range_first: start_key 1 end_key 4

id >= 2 and id <= 8
records_in_range: start_key 0 end_key 3
read_range_first: start_key 1 end_key 3

id > 2 and id <= 8
records_in_range: start_key 3 end_key 3
read_range_first: start_key 3 end_key 3

multi keys (id int, name varchar, other varchar)

id = 1;
records_in_range: start_key 0 end_key 3
read_range_first: start_key 0 end_key NULL

id > 4;
id > 2 and name = '333'; remote: id > 2
id > 2 and name > '333'; remote: id > 2
id > 2 and name > '333' and other < 'ddd'; remote: id > 2 no results
id > 2 and name >= '333' and other < 'ddd'; remote: id > 2 1 result
id >= 4 and name = 'eric was here' and other > 'eeee';
records_in_range: start_key 3 end_key NULL
read_range_first: start_key 3 end_key NULL

id >= 4;
id >= 2 and name = '333' and other < 'ddd';
remote: `id`  >= 2 AND `name`  >= '333';
records_in_range: start_key 0 end_key NULL
read_range_first: start_key 1 end_key NULL

id < 4;
id < 3 and name = '222' and other <= 'ccc'; remote: id < 3
records_in_range: start_key NULL end_key 4
read_range_first: start_key NULL end_key 4

id <= 4;
records_in_range: start_key NULL end_key 3
read_range_first: start_key NULL end_key 3

id like 4;
full table scan

id  > 2 and id < 4;
records_in_range: start_key 3 end_key 4
read_range_first: start_key 3 end_key 4

id >= 2 and id < 4;
records_in_range: start_key 0 end_key 4
read_range_first: start_key 1 end_key 4

id >= 2 and id <= 4;
records_in_range: start_key 0 end_key 3
read_range_first: start_key 1 end_key 3

id > 2 and id <= 4;
id = 6 and name = 'eric was here' and other > 'eeee';
remote: (`id`  > 6 AND `name`  > 'eric was here' AND `other`  > 'eeee')
AND (`id`  <= 6) AND ( AND `name`  <= 'eric was here')
no results
records_in_range: start_key 3 end_key 3
read_range_first: start_key 3 end_key 3

Summary:

* If the start key flag is 0 the max key flag shouldn't even be set, 
  and if it is, the query produced would be invalid.
* Multipart keys, even if containing some or all numeric columns,
  are treated the same as non-numeric keys

  If the query is " = " (quotes or not):
  - records in range start key flag HA_READ_KEY_EXACT,
    end key flag HA_READ_AFTER_KEY (incorrect)
  - any other: start key flag HA_READ_KEY_OR_NEXT,
    end key flag HA_READ_AFTER_KEY (correct)

* 'like' queries (of key)
  - Numeric, full table scan
  - Non-numeric
      records_in_range: start_key 0 end_key 3
      other : start_key 1 end_key 3

* If the key flag is HA_READ_AFTER_KEY:
   if start_key, append >
   if end_key, append <=

* If create_where_key was called by records_in_range:

 - if the key is numeric:
    start key flag is 0 when end key is NULL, end key flag is 3 or 4
 - if create_where_key was called by any other function:
    start key flag is 1 when end key is NULL, end key flag is 3 or 4
 - if the key is non-numeric, or multipart
    When the query is an exact match, the start key flag is 0,
    end key flag is 3 for what should be a no-range condition where
    you should have 0 and max key NULL, which it is if called by
    read_range_first

Conclusion:

1. Need logic to determin if a key is min or max when the flag is
HA_READ_AFTER_KEY, and handle appending correct operator accordingly

2. Need a boolean flag to pass to create_where_from_key, used in the
switch statement. Add 1 to the flag if:
  - start key flag is HA_READ_KEY_EXACT and the end key is NULL

*/

bool ha_federated::create_where_from_key(String *to,
                                         KEY *key_info,
                                         const key_range *start_key,
                                         const key_range *end_key,
1226 1227
                                         bool records_in_range,
                                         bool eq_range)
1228
{
1229
  bool both_not_null=
1230
    (start_key != NULL && end_key != NULL) ? TRUE : FALSE;
1231 1232 1233 1234 1235
  const byte *ptr;
  uint remainder, length;
  char tmpbuff[FEDERATED_QUERY_BUFFER_SIZE];
  String tmp(tmpbuff, sizeof(tmpbuff), system_charset_info);
  const key_range *ranges[2]= { start_key, end_key };
1236
  my_bitmap_map *old_map;
1237
  DBUG_ENTER("ha_federated::create_where_from_key");
1238

1239 1240 1241
  tmp.length(0); 
  if (start_key == NULL && end_key == NULL)
    DBUG_RETURN(1);
1242

1243 1244
  old_map= dbug_tmp_use_all_columns(table, table->write_set);
  for (uint i= 0; i <= 1; i++)
1245 1246 1247 1248 1249
  {
    bool needs_quotes;
    KEY_PART_INFO *key_part;
    if (ranges[i] == NULL)
      continue;
1250

1251
    if (both_not_null)
1252
    {
1253
      if (i > 0)
1254
        tmp.append(STRING_WITH_LEN(") AND ("));
1255
      else
1256
        tmp.append(STRING_WITH_LEN(" ("));
1257
    }
1258

1259 1260 1261 1262 1263 1264
    for (key_part= key_info->key_part,
         remainder= key_info->key_parts,
         length= ranges[i]->length,
         ptr= ranges[i]->key; ;
         remainder--,
         key_part++)
1265
    {
1266 1267 1268
      Field *field= key_part->field;
      uint store_length= key_part->store_length;
      uint part_length= min(store_length, length);
1269
      needs_quotes= field->str_needs_quotes();
1270
      DBUG_DUMP("key, start of loop", (char *) ptr, length);
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1271

1272 1273 1274 1275 1276
      if (key_part->null_bit)
      {
        if (*ptr++)
        {
          if (emit_key_part_name(&tmp, key_part) ||
1277
              tmp.append(STRING_WITH_LEN(" IS NULL ")))
1278
            goto err;
1279 1280 1281
          continue;
        }
      }
1282

1283
      if (tmp.append(STRING_WITH_LEN(" (")))
1284
        goto err;
1285

1286 1287
      switch (ranges[i]->flag) {
      case HA_READ_KEY_EXACT:
1288
        DBUG_PRINT("info", ("federated HA_READ_KEY_EXACT %d", i));
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        if (store_length >= length ||
            !needs_quotes ||
            key_part->type == HA_KEYTYPE_BIT ||
            field->result_type() != STRING_RESULT)
        {
          if (emit_key_part_name(&tmp, key_part))
1295
            goto err;
1296 1297 1298

          if (records_in_range)
          {
1299
            if (tmp.append(STRING_WITH_LEN(" >= ")))
1300
              goto err;
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          }
          else
          {
1304
            if (tmp.append(STRING_WITH_LEN(" = ")))
1305
              goto err;
1306
          }
1307

1308 1309
          if (emit_key_part_element(&tmp, key_part, needs_quotes, 0, ptr,
                                    part_length))
1310
            goto err;
1311 1312 1313
        }
        else
        {
1314
          /* LIKE */
1315
          if (emit_key_part_name(&tmp, key_part) ||
1316
              tmp.append(STRING_WITH_LEN(" LIKE ")) ||
1317 1318
              emit_key_part_element(&tmp, key_part, needs_quotes, 1, ptr,
                                    part_length))
1319
            goto err;
1320 1321
        }
        break;
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      case HA_READ_AFTER_KEY:
        if (eq_range)
        {
          if (tmp.append("1=1"))                // Dummy
            goto err;
          break;
        }
1329
        DBUG_PRINT("info", ("federated HA_READ_AFTER_KEY %d", i));
1330 1331 1332
        if (store_length >= length) /* end key */
        {
          if (emit_key_part_name(&tmp, key_part))
1333
            goto err;
1334 1335

          if (i > 0) /* end key */
1336
          {
1337
            if (tmp.append(STRING_WITH_LEN(" <= ")))
1338
              goto err;
1339
          }
1340
          else /* start key */
1341
          {
1342
            if (tmp.append(STRING_WITH_LEN(" > ")))
1343
              goto err;
1344
          }
1345 1346

          if (emit_key_part_element(&tmp, key_part, needs_quotes, 0, ptr,
1347 1348
                                    part_length))
          {
1349
            goto err;
1350
          }
1351 1352
          break;
        }
1353
      case HA_READ_KEY_OR_NEXT:
1354
        DBUG_PRINT("info", ("federated HA_READ_KEY_OR_NEXT %d", i));
1355
        if (emit_key_part_name(&tmp, key_part) ||
1356
            tmp.append(STRING_WITH_LEN(" >= ")) ||
1357
            emit_key_part_element(&tmp, key_part, needs_quotes, 0, ptr,
1358
              part_length))
1359
          goto err;
1360
        break;
1361
      case HA_READ_BEFORE_KEY:
1362
        DBUG_PRINT("info", ("federated HA_READ_BEFORE_KEY %d", i));
1363 1364 1365
        if (store_length >= length)
        {
          if (emit_key_part_name(&tmp, key_part) ||
1366
              tmp.append(STRING_WITH_LEN(" < ")) ||
1367 1368
              emit_key_part_element(&tmp, key_part, needs_quotes, 0, ptr,
                                    part_length))
1369
            goto err;
1370 1371
          break;
        }
1372
      case HA_READ_KEY_OR_PREV:
1373
        DBUG_PRINT("info", ("federated HA_READ_KEY_OR_PREV %d", i));
1374
        if (emit_key_part_name(&tmp, key_part) ||
1375
            tmp.append(STRING_WITH_LEN(" <= ")) ||
1376 1377
            emit_key_part_element(&tmp, key_part, needs_quotes, 0, ptr,
                                  part_length))
1378
          goto err;
1379 1380 1381
        break;
      default:
        DBUG_PRINT("info",("cannot handle flag %d", ranges[i]->flag));
1382
        goto err;
1383
      }
1384
      if (tmp.append(STRING_WITH_LEN(") ")))
1385
        goto err;
1386 1387 1388 1389 1390 1391 1392

      if (store_length >= length)
        break;
      DBUG_PRINT("info", ("remainder %d", remainder));
      DBUG_ASSERT(remainder > 1);
      length-= store_length;
      ptr+= store_length;
1393
      if (tmp.append(STRING_WITH_LEN(" AND ")))
1394
        goto err;
1395 1396 1397 1398

      DBUG_PRINT("info",
                 ("create_where_from_key WHERE clause: %s",
                  tmp.c_ptr_quick()));
1399
    }
1400
  }
1401 1402
  dbug_tmp_restore_column_map(table->write_set, old_map);

1403
  if (both_not_null)
1404
    if (tmp.append(STRING_WITH_LEN(") ")))
1405
      DBUG_RETURN(1);
1406

1407
  if (to->append(STRING_WITH_LEN(" WHERE ")))
1408 1409 1410 1411 1412 1413
    DBUG_RETURN(1);

  if (to->append(tmp))
    DBUG_RETURN(1);

  DBUG_RETURN(0);
1414 1415 1416 1417

err:
  dbug_tmp_restore_column_map(table->write_set, old_map);
  DBUG_RETURN(1);
1418 1419 1420 1421 1422 1423 1424
}

/*
  Example of simple lock controls. The "share" it creates is structure we will
  pass to each federated handler. Do you have to have one of these? Well, you
  have pieces that are used for locking, and they are needed to function.
*/
1425

1426 1427
static FEDERATED_SHARE *get_share(const char *table_name, TABLE *table)
{
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  char *select_query;
1429 1430
  char query_buffer[FEDERATED_QUERY_BUFFER_SIZE];
  Field **field;
1431
  String query(query_buffer, sizeof(query_buffer), &my_charset_bin);
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1432
  FEDERATED_SHARE *share= NULL, tmp_share;
1433 1434 1435
  /*
    In order to use this string, we must first zero it's length,
    or it will contain garbage
1436
  */
1437 1438 1439 1440
  query.length(0);

  pthread_mutex_lock(&federated_mutex);

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1441 1442
  tmp_share.share_key= table_name;
  tmp_share.share_key_length= strlen(table_name);
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1443 1444 1445 1446
  if (parse_url(&tmp_share, table, 0))
    goto error;

  /* TODO: change tmp_share.scheme to LEX_STRING object */
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1447
  if (!(share= (FEDERATED_SHARE *) hash_search(&federated_open_tables,
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1448
                                               (byte*) tmp_share.share_key,
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1449
                                               tmp_share.
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1450
                                               share_key_length)))
1451 1452
  {
    query.set_charset(system_charset_info);
1453
    query.append(STRING_WITH_LEN("SELECT "));
1454 1455
    for (field= table->field; *field; field++)
    {
1456
      query.append(STRING_WITH_LEN("`"));
1457
      query.append((*field)->field_name);
1458
      query.append(STRING_WITH_LEN("`, "));
1459
    }
1460 1461 1462 1463
    /* chops off trailing comma */
    query.length(query.length() - sizeof_trailing_comma);

    query.append(STRING_WITH_LEN(" FROM `"));
1464

1465
    if (!(share= (FEDERATED_SHARE *)
1466
          my_multi_malloc(MYF(MY_WME),
1467
                          &share, sizeof(*share),
1468
                          &select_query,
1469
                          query.length()+table->s->connect_string.length+1,
1470
                          NullS)))
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1471 1472
      goto error;

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    memcpy(share, &tmp_share, sizeof(tmp_share));

    share->table_name_length= strlen(share->table_name);
    /* TODO: share->table_name to LEX_STRING object */
1477
    query.append(share->table_name, share->table_name_length);
1478
    query.append(STRING_WITH_LEN("`"));
1479
    share->select_query= select_query;
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1480
    strmov(share->select_query, query.ptr());
1481
    share->use_count= 0;
1482
    DBUG_PRINT("info",
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1483
               ("share->select_query %s", share->select_query));
1484

1485 1486 1487
    if (my_hash_insert(&federated_open_tables, (byte*) share))
      goto error;
    thr_lock_init(&share->lock);
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1488
    pthread_mutex_init(&share->mutex, MY_MUTEX_INIT_FAST);
1489 1490 1491 1492 1493 1494 1495 1496
  }
  share->use_count++;
  pthread_mutex_unlock(&federated_mutex);

  return share;

error:
  pthread_mutex_unlock(&federated_mutex);
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  my_free((gptr) tmp_share.connection_string, MYF(MY_ALLOW_ZERO_PTR));
  tmp_share.connection_string= 0;
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  my_free((gptr) share, MYF(MY_ALLOW_ZERO_PTR));
1500 1501 1502 1503 1504
  return NULL;
}


/*
1505
  Free lock controls. We call this whenever we close a table.
1506 1507 1508
  If the table had the last reference to the share then we
  free memory associated with it.
*/
1509

1510 1511
static int free_share(FEDERATED_SHARE *share)
{
1512
  DBUG_ENTER("free_share");
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1513

1514
  pthread_mutex_lock(&federated_mutex);
1515 1516 1517
  if (!--share->use_count)
  {
    hash_delete(&federated_open_tables, (byte*) share);
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1518 1519
    if (share->parsed)
      my_free((gptr) share->socket, MYF(MY_ALLOW_ZERO_PTR));
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1520
    /*if (share->connection_string)
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1521
    {
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1522
    */
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1523 1524
      my_free((gptr) share->connection_string, MYF(MY_ALLOW_ZERO_PTR));
      share->connection_string= 0;
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1525
      /*}*/
1526
    thr_lock_delete(&share->lock);
1527
    VOID(pthread_mutex_destroy(&share->mutex));
1528 1529 1530 1531
    my_free((gptr) share, MYF(0));
  }
  pthread_mutex_unlock(&federated_mutex);

1532
  DBUG_RETURN(0);
1533 1534 1535
}


1536 1537 1538 1539 1540
ha_rows ha_federated::records_in_range(uint inx, key_range *start_key,
                                   key_range *end_key)
{
  /*

1541 1542 1543
  We really want indexes to be used as often as possible, therefore
  we just need to hard-code the return value to a very low number to
  force the issue
1544 1545 1546 1547 1548

*/
  DBUG_ENTER("ha_federated::records_in_range");
  DBUG_RETURN(FEDERATED_RECORDS_IN_RANGE);
}
1549 1550
/*
  If frm_error() is called then we will use this to to find out
1551 1552
  what file extentions exist for the storage engine. This is
  also used by the default rename_table and delete_table method
1553 1554
  in handler.cc.
*/
1555

1556
const char **ha_federated::bas_ext() const
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1557
{
1558 1559 1560 1561 1562
  static const char *ext[]=
  {
    NullS
  };
  return ext;
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1563
}
1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575


/*
  Used for opening tables. The name will be the name of the file.
  A table is opened when it needs to be opened. For instance
  when a request comes in for a select on the table (tables are not
  open and closed for each request, they are cached).

  Called from handler.cc by handler::ha_open(). The server opens
  all tables by calling ha_open() which then calls the handler
  specific open().
*/
1576

1577 1578
int ha_federated::open(const char *name, int mode, uint test_if_locked)
{
1579
  DBUG_ENTER("ha_federated::open");
1580 1581 1582

  if (!(share= get_share(name, table)))
    DBUG_RETURN(1);
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1583
  thr_lock_data_init(&share->lock, &lock, NULL);
1584

1585
  /* Connect to foreign database mysql_real_connect() */
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1586
  mysql= mysql_init(0);
1587 1588 1589 1590 1591 1592 1593 1594 1595 1596

  /*
    BUG# 17044 Federated Storage Engine is not UTF8 clean
    Add set names to whatever charset the table is at open
    of table
  */
  /* this sets the csname like 'set names utf8' */
  mysql_options(mysql,MYSQL_SET_CHARSET_NAME,
                this->table->s->table_charset->csname);

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1597 1598 1599 1600 1601 1602 1603
  if (!mysql || !mysql_real_connect(mysql,
                                   share->hostname,
                                   share->username,
                                   share->password,
                                   share->database,
                                   share->port,
                                   share->socket, 0))
1604
  {
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1605
    free_share(share);
1606
    DBUG_RETURN(stash_remote_error());
1607
  }
1608 1609
  /*
    Since we do not support transactions at this version, we can let the client
1610 1611
    API silently reconnect. For future versions, we will need more logic to
    deal with transactions
1612
  */
1613

1614
  mysql->reconnect= 1;
1615

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1616 1617 1618 1619 1620
  ref_length= (table->s->primary_key != MAX_KEY ?
               table->key_info[table->s->primary_key].key_length :
               table->s->reclength);
  DBUG_PRINT("info", ("ref_length: %u", ref_length));

1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634
  DBUG_RETURN(0);
}


/*
  Closes a table. We call the free_share() function to free any resources
  that we have allocated in the "shared" structure.

  Called from sql_base.cc, sql_select.cc, and table.cc.
  In sql_select.cc it is only used to close up temporary tables or during
  the process where a temporary table is converted over to being a
  myisam table.
  For sql_base.cc look at close_data_tables().
*/
1635

1636 1637
int ha_federated::close(void)
{
1638
  int retval;
1639
  DBUG_ENTER("ha_federated::close");
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1640

1641
  /* free the result set */
1642
  if (stored_result)
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1643
  {
1644 1645
    mysql_free_result(stored_result);
    stored_result= 0;
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1646
  }
1647
  /* Disconnect from mysql */
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1648 1649
  if (mysql)                                    // QQ is this really needed
    mysql_close(mysql);
1650 1651
  retval= free_share(share);
  DBUG_RETURN(retval);
1652 1653 1654 1655 1656

}

/*

1657
  Checks if a field in a record is SQL NULL.
1658 1659 1660 1661 1662 1663 1664 1665 1666

  SYNOPSIS
    field_in_record_is_null()
      table     TABLE pointer, MySQL table object
      field     Field pointer, MySQL field object
      record    char pointer, contains record

    DESCRIPTION
      This method uses the record format information in table to track
1667
      the null bit in record.
1668 1669 1670

    RETURN VALUE
      1    if NULL
1671
      0    otherwise
1672
*/
1673

1674
static inline uint field_in_record_is_null(TABLE *table,
1675 1676
                                    Field *field,
                                    char *record)
1677 1678 1679 1680 1681 1682 1683
{
  int null_offset;
  DBUG_ENTER("ha_federated::field_in_record_is_null");

  if (!field->null_ptr)
    DBUG_RETURN(0);

1684
  null_offset= (uint) ((char*)field->null_ptr - (char*)table->record[0]);
1685 1686 1687 1688 1689 1690 1691

  if (record[null_offset] & field->null_bit)
    DBUG_RETURN(1);

  DBUG_RETURN(0);
}

1692

1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705
/*
  write_row() inserts a row. No extra() hint is given currently if a bulk load
  is happeneding. buf() is a byte array of data. You can use the field
  information to extract the data from the native byte array type.
  Example of this would be:
  for (Field **field=table->field ; *field ; field++)
  {
    ...
  }

  Called from item_sum.cc, item_sum.cc, sql_acl.cc, sql_insert.cc,
  sql_insert.cc, sql_select.cc, sql_table.cc, sql_udf.cc, and sql_update.cc.
*/
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int ha_federated::write_row(byte *buf)
1708
{
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  /*
    I need a bool again, in 5.0, I used table->s->fields to accomplish this.
    This worked as a flag that says there are fields with values or not.
    In 5.1, this value doesn't work the same, and I end up with the code
    truncating open parenthesis:

    the statement "INSERT INTO t1 VALUES ()" ends up being first built
    in two strings
      "INSERT INTO t1 ("
      and
      " VALUES ("

    If there are fields with values, they get appended, with commas, and 
    the last loop, a trailing comma is there

    "INSERT INTO t1 ( col1, col2, colN, "

    " VALUES ( 'val1', 'val2', 'valN', "

    Then, if there are fields, it should decrement the string by ", " length.

    "INSERT INTO t1 ( col1, col2, colN"
    " VALUES ( 'val1', 'val2', 'valN'"

    Then it adds a close paren to both - if there are fields

    "INSERT INTO t1 ( col1, col2, colN)"
    " VALUES ( 'val1', 'val2', 'valN')"

    Then appends both together
    "INSERT INTO t1 ( col1, col2, colN) VALUES ( 'val1', 'val2', 'valN')"

    So... the problem, is if you have the original statement:

    "INSERT INTO t1 VALUES ()"

    Which is legitimate, but if the code thinks there are fields

    "INSERT INTO t1 ("
    " VALUES ( "

    If the field flag is set, but there are no commas, reduces the 
    string by strlen(", ")

    "INSERT INTO t1 "
    " VALUES "

    Then adds the close parenthesis

    "INSERT INTO t1  )"
    " VALUES  )"

    So, I have to use a bool as before, set in the loop where fields and commas
    are appended to the string
  */
  my_bool commas_added= FALSE;
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  char insert_buffer[FEDERATED_QUERY_BUFFER_SIZE];
  char values_buffer[FEDERATED_QUERY_BUFFER_SIZE];
  char insert_field_value_buffer[STRING_BUFFER_USUAL_SIZE];
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  Field **field;
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  /* The main insert query string */
1771
  String insert_string(insert_buffer, sizeof(insert_buffer), &my_charset_bin);
1772
  /* The string containing the values to be added to the insert */
1773
  String values_string(values_buffer, sizeof(values_buffer), &my_charset_bin);
1774
  /* The actual value of the field, to be added to the values_string */
1775
  String insert_field_value_string(insert_field_value_buffer,
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                                   sizeof(insert_field_value_buffer),
                                   &my_charset_bin);
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  my_bitmap_map *old_map= dbug_tmp_use_all_columns(table, table->read_set);
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  DBUG_ENTER("ha_federated::write_row");
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  values_string.length(0);
  insert_string.length(0);
  insert_field_value_string.length(0);
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  statistic_increment(table->in_use->status_var.ha_write_count, &LOCK_status);
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  if (table->timestamp_field_type & TIMESTAMP_AUTO_SET_ON_INSERT)
    table->timestamp_field->set_time();

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  /*
    start both our field and field values strings
  */
1791
  insert_string.append(STRING_WITH_LEN("INSERT INTO `"));
1792
  insert_string.append(share->table_name, share->table_name_length);
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  insert_string.append('`');
  insert_string.append(STRING_WITH_LEN(" ("));
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  values_string.append(STRING_WITH_LEN(" VALUES "));
  values_string.append(STRING_WITH_LEN(" ("));
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  /*
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    loop through the field pointer array, add any fields to both the values
1801
    list and the fields list that is part of the write set
1802
  */
1803
  for (field= table->field; *field; field++)
1804
  {
1805
    if (bitmap_is_set(table->write_set, (*field)->field_index))
1806
    {
1807
      commas_added= TRUE;
1808
      if ((*field)->is_null())
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        values_string.append(STRING_WITH_LEN(" NULL "));
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      else
      {
1812
        bool needs_quote= (*field)->str_needs_quotes();
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        (*field)->val_str(&insert_field_value_string);
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        if (needs_quote)
          values_string.append('\'');
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        insert_field_value_string.print(&values_string);
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        if (needs_quote)
          values_string.append('\'');
1819

1820
        insert_field_value_string.length(0);
1821
      }
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      /* append the field name */
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      insert_string.append((*field)->field_name);

1825
      /* append commas between both fields and fieldnames */
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      /*
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        unfortunately, we can't use the logic if *(fields + 1) to
        make the following appends conditional as we don't know if the
        next field is in the write set
1830
      */
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      insert_string.append(STRING_WITH_LEN(", "));
      values_string.append(STRING_WITH_LEN(", "));
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    }
  }
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  dbug_tmp_restore_column_map(table->read_set, old_map);
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  /*
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    if there were no fields, we don't want to add a closing paren
    AND, we don't want to chop off the last char '('
    insert will be "INSERT INTO t1 VALUES ();"
1841
  */
1842
  if (commas_added)
1843
  {
1844
    insert_string.length(insert_string.length() - sizeof_trailing_comma);
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    /* chops off leading commas */
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    values_string.length(values_string.length() - sizeof_trailing_comma);
    insert_string.append(STRING_WITH_LEN(") "));
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  }
1849
  else
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  {
    /* chops off trailing ) */
    insert_string.length(insert_string.length() - sizeof_trailing_closeparen);
  }
1854

1855
  /* we always want to append this, even if there aren't any fields */
1856
  values_string.append(STRING_WITH_LEN(") "));
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1858
  /* add the values */
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  insert_string.append(values_string);

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  if (mysql_real_query(mysql, insert_string.ptr(), insert_string.length()))
1862
  {
1863
    DBUG_RETURN(stash_remote_error());
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  }
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  /*
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    If the table we've just written a record to contains an auto_increment
    field, then store the last_insert_id() value from the foreign server
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  */
  if (table->next_number_field)
    update_auto_increment();
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  DBUG_RETURN(0);
}

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/*
  ha_federated::update_auto_increment

  This method ensures that last_insert_id() works properly. What it simply does
  is calls last_insert_id() on the foreign database immediately after insert
  (if the table has an auto_increment field) and sets the insert id via
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  thd->insert_id(ID)).
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*/
void ha_federated::update_auto_increment(void)
{
  THD *thd= current_thd;
  DBUG_ENTER("ha_federated::update_auto_increment");

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  thd->first_successful_insert_id_in_cur_stmt= 
    mysql->last_used_con->insert_id;
1890
  DBUG_PRINT("info",("last_insert_id: %ld", (long) stats.auto_increment_value));
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  DBUG_VOID_RETURN;
}
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int ha_federated::optimize(THD* thd, HA_CHECK_OPT* check_opt)
{
  char query_buffer[STRING_BUFFER_USUAL_SIZE];
  String query(query_buffer, sizeof(query_buffer), &my_charset_bin);
  DBUG_ENTER("ha_federated::optimize");
  
  query.length(0);

  query.set_charset(system_charset_info);
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  query.append(STRING_WITH_LEN("OPTIMIZE TABLE `"));
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  query.append(share->table_name, share->table_name_length);
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  query.append(STRING_WITH_LEN("`"));
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  if (mysql_real_query(mysql, query.ptr(), query.length()))
  {
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    DBUG_RETURN(stash_remote_error());
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  }

  DBUG_RETURN(0);
}


int ha_federated::repair(THD* thd, HA_CHECK_OPT* check_opt)
{
  char query_buffer[STRING_BUFFER_USUAL_SIZE];
  String query(query_buffer, sizeof(query_buffer), &my_charset_bin);
  DBUG_ENTER("ha_federated::repair");

  query.length(0);

  query.set_charset(system_charset_info);
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  query.append(STRING_WITH_LEN("REPAIR TABLE `"));
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  query.append(share->table_name, share->table_name_length);
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  query.append(STRING_WITH_LEN("`"));
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  if (check_opt->flags & T_QUICK)
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    query.append(STRING_WITH_LEN(" QUICK"));
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  if (check_opt->flags & T_EXTEND)
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    query.append(STRING_WITH_LEN(" EXTENDED"));
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  if (check_opt->sql_flags & TT_USEFRM)
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    query.append(STRING_WITH_LEN(" USE_FRM"));
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1936 1937
  if (mysql_real_query(mysql, query.ptr(), query.length()))
  {
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    DBUG_RETURN(stash_remote_error());
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  }

  DBUG_RETURN(0);
}

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/*
  Yes, update_row() does what you expect, it updates a row. old_data will have
  the previous row record in it, while new_data will have the newest data in
  it.

  Keep in mind that the server can do updates based on ordering if an ORDER BY
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  clause was used. Consecutive ordering is not guaranteed.
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  Currently new_data will not have an updated auto_increament record, or
  and updated timestamp field. You can do these for federated by doing these:
  if (table->timestamp_on_update_now)
    update_timestamp(new_row+table->timestamp_on_update_now-1);
  if (table->next_number_field && record == table->record[0])
    update_auto_increment();

  Called from sql_select.cc, sql_acl.cc, sql_update.cc, and sql_insert.cc.
*/
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1962
int ha_federated::update_row(const byte *old_data, byte *new_data)
1963
{
1964
  /*
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    This used to control how the query was built. If there was a
    primary key, the query would be built such that there was a where
    clause with only that column as the condition. This is flawed,
    because if we have a multi-part primary key, it would only use the
    first part! We don't need to do this anyway, because
    read_range_first will retrieve the correct record, which is what
    is used to build the WHERE clause. We can however use this to
    append a LIMIT to the end if there is NOT a primary key. Why do
    this? Because we only are updating one record, and LIMIT enforces
    this.
1975
  */
1976
  bool has_a_primary_key= test(table->s->primary_key != MAX_KEY);
1977
  
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  /*
1979 1980
    buffers for following strings
  */
1981
  char field_value_buffer[STRING_BUFFER_USUAL_SIZE];
1982 1983
  char update_buffer[FEDERATED_QUERY_BUFFER_SIZE];
  char where_buffer[FEDERATED_QUERY_BUFFER_SIZE];
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  /* Work area for field values */
  String field_value(field_value_buffer, sizeof(field_value_buffer),
                     &my_charset_bin);
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  /* stores the update query */
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  String update_string(update_buffer,
                       sizeof(update_buffer),
                       &my_charset_bin);
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  /* stores the WHERE clause */
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  String where_string(where_buffer,
                      sizeof(where_buffer),
                      &my_charset_bin);
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  byte *record= table->record[0];
1997
  DBUG_ENTER("ha_federated::update_row");
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  /*
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    set string lengths to 0 to avoid misc chars in string
  */
2001
  field_value.length(0);
2002 2003
  update_string.length(0);
  where_string.length(0);
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2005
  update_string.append(STRING_WITH_LEN("UPDATE `"));
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  update_string.append(share->table_name);
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  update_string.append(STRING_WITH_LEN("` SET "));
2008

2009 2010 2011
  /*
    In this loop, we want to match column names to values being inserted
    (while building INSERT statement).
2012

2013 2014
    Iterate through table->field (new data) and share->old_field (old_data)
    using the same index to create an SQL UPDATE statement. New data is
2015 2016 2017
    used to create SET field=value and old data is used to create WHERE
    field=oldvalue
  */
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2018

2019
  for (Field **field= table->field; *field; field++)
2020
  {
2021
    if (bitmap_is_set(table->write_set, (*field)->field_index))
2022
    {
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2023
      update_string.append((*field)->field_name);
2024
      update_string.append(STRING_WITH_LEN(" = "));
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2025

2026
      if ((*field)->is_null())
2027
        update_string.append(STRING_WITH_LEN(" NULL "));
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      else
      {
        /* otherwise = */
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        my_bitmap_map *old_map= tmp_use_all_columns(table, table->read_set);
        bool needs_quote= (*field)->str_needs_quotes();
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	(*field)->val_str(&field_value);
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        if (needs_quote)
          update_string.append('\'');
2036
        field_value.print(&update_string);
2037 2038
        if (needs_quote)
          update_string.append('\'');
2039
        field_value.length(0);
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        tmp_restore_column_map(table->read_set, old_map);
      }
2042
      update_string.append(STRING_WITH_LEN(", "));
2043
    }
2044

2045
    if (bitmap_is_set(table->read_set, (*field)->field_index))
2046
    {
2047 2048
      where_string.append((*field)->field_name);
      if (field_in_record_is_null(table, *field, (char*) old_data))
2049
        where_string.append(STRING_WITH_LEN(" IS NULL "));
2050 2051
      else
      {
2052
        bool needs_quote= (*field)->str_needs_quotes();
2053
        where_string.append(STRING_WITH_LEN(" = "));
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        (*field)->val_str(&field_value,
2055
                          (char*) (old_data + (*field)->offset(record)));
2056 2057
        if (needs_quote)
          where_string.append('\'');
2058
        field_value.print(&where_string);
2059 2060
        if (needs_quote)
          where_string.append('\'');
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        field_value.length(0);
2062
      }
2063
      where_string.append(STRING_WITH_LEN(" AND "));
2064 2065
    }
  }
2066 2067

  /* Remove last ', '. This works as there must be at least on updated field */
2068
  update_string.length(update_string.length() - sizeof_trailing_comma);
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2070 2071
  if (where_string.length())
  {
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    /* chop off trailing AND */
    where_string.length(where_string.length() - sizeof_trailing_and);
    update_string.append(STRING_WITH_LEN(" WHERE "));
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    update_string.append(where_string);
  }

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  /*
    If this table has not a primary key, then we could possibly
    update multiple rows. We want to make sure to only update one!
  */
2082
  if (!has_a_primary_key)
2083
    update_string.append(STRING_WITH_LEN(" LIMIT 1"));
2084

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2085
  if (mysql_real_query(mysql, update_string.ptr(), update_string.length()))
2086
  {
2087
    DBUG_RETURN(stash_remote_error());
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  }
  DBUG_RETURN(0);
}

/*
2093
  This will delete a row. 'buf' will contain a copy of the row to be =deleted.
2094
  The server will call this right after the current row has been called (from
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2095
  either a previous rnd_next() or index call).
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  If you keep a pointer to the last row or can access a primary key it will
  make doing the deletion quite a bit easier.
  Keep in mind that the server does no guarentee consecutive deletions.
  ORDER BY clauses can be used.

  Called in sql_acl.cc and sql_udf.cc to manage internal table information.
2102
  Called in sql_delete.cc, sql_insert.cc, and sql_select.cc. In sql_select
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  it is used for removing duplicates while in insert it is used for REPLACE
  calls.
*/
2106

2107
int ha_federated::delete_row(const byte *buf)
2108
{
2109 2110
  char delete_buffer[FEDERATED_QUERY_BUFFER_SIZE];
  char data_buffer[FEDERATED_QUERY_BUFFER_SIZE];
2111 2112
  String delete_string(delete_buffer, sizeof(delete_buffer), &my_charset_bin);
  String data_string(data_buffer, sizeof(data_buffer), &my_charset_bin);
2113
  uint found= 0;
2114 2115
  DBUG_ENTER("ha_federated::delete_row");

2116
  delete_string.length(0);
2117
  delete_string.append(STRING_WITH_LEN("DELETE FROM `"));
2118
  delete_string.append(share->table_name);
2119
  delete_string.append(STRING_WITH_LEN("` WHERE "));
2120

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2121
  for (Field **field= table->field; *field; field++)
2122
  {
2123
    Field *cur_field= *field;
2124 2125
    found++;
    if (bitmap_is_set(table->read_set, cur_field->field_index))
2126
    {
2127 2128 2129 2130
      data_string.length(0);
      delete_string.append(cur_field->field_name);
      if (cur_field->is_null())
      {
2131
        delete_string.append(STRING_WITH_LEN(" IS NULL "));
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      }
      else
      {
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        bool needs_quote= cur_field->str_needs_quotes();
        delete_string.append(STRING_WITH_LEN(" = "));
        cur_field->val_str(&data_string);
        if (needs_quote)
          delete_string.append('\'');
        data_string.print(&delete_string);
        if (needs_quote)
          delete_string.append('\'');
2143
      }
2144
      delete_string.append(STRING_WITH_LEN(" AND "));
2145 2146
    }
  }
2147

2148 2149
  // Remove trailing AND
  delete_string.length(delete_string.length() - sizeof_trailing_and);
2150
  if (!found)
2151
    delete_string.length(delete_string.length() - sizeof_trailing_where);
2152

2153
  delete_string.append(STRING_WITH_LEN(" LIMIT 1"));
2154
  DBUG_PRINT("info",
2155
             ("Delete sql: %s", delete_string.c_ptr_quick()));
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2156
  if (mysql_real_query(mysql, delete_string.ptr(), delete_string.length()))
2157
  {
2158
    DBUG_RETURN(stash_remote_error());
2159
  }
2160 2161
  stats.deleted+= (ha_rows) mysql->affected_rows;
  stats.records-= (ha_rows) mysql->affected_rows;
2162
  DBUG_PRINT("info",
2163
             ("rows deleted %ld  rows deleted for all time %ld",
2164
              (long) mysql->affected_rows, (long) stats.deleted));
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  DBUG_RETURN(0);
}


/*
  Positions an index cursor to the index specified in the handle. Fetches the
  row if available. If the key value is null, begin at the first key of the
  index. This method, which is called in the case of an SQL statement having
  a WHERE clause on a non-primary key index, simply calls index_read_idx.
*/
2176

2177
int ha_federated::index_read(byte *buf, const byte *key,
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                             uint key_len, ha_rkey_function find_flag)
2179 2180
{
  DBUG_ENTER("ha_federated::index_read");
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  if (stored_result)
    mysql_free_result(stored_result);
  DBUG_RETURN(index_read_idx_with_result_set(buf, active_index, key,
                                             key_len, find_flag,
                                             &stored_result));
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}


/*
  Positions an index cursor to the index specified in key. Fetches the
  row if any.  This is only used to read whole keys.

  This method is called via index_read in the case of a WHERE clause using
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  a primary key index OR is called DIRECTLY when the WHERE clause
2196
  uses a PRIMARY KEY index.
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  NOTES
    This uses an internal result set that is deleted before function
    returns.  We need to be able to be calable from ha_rnd_pos()
2201
*/
2202

2203
int ha_federated::index_read_idx(byte *buf, uint index, const byte *key,
2204
                                 uint key_len, enum ha_rkey_function find_flag)
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{
  int retval;
  MYSQL_RES *mysql_result;
  DBUG_ENTER("ha_federated::index_read_idx");

  if ((retval= index_read_idx_with_result_set(buf, index, key,
                                              key_len, find_flag,
                                              &mysql_result)))
    DBUG_RETURN(retval);
  mysql_free_result(mysql_result);
  DBUG_RETURN(retval);
}


/*
  Create result set for rows matching query and return first row

  RESULT
    0	ok     In this case *result will contain the result set
	       table->status == 0 
    #   error  In this case *result will contain 0
               table->status == STATUS_NOT_FOUND
*/

int ha_federated::index_read_idx_with_result_set(byte *buf, uint index,
                                                 const byte *key,
                                                 uint key_len,
                                                 ha_rkey_function find_flag,
                                                 MYSQL_RES **result)
2234
{
2235 2236 2237 2238
  int retval;
  char error_buffer[FEDERATED_QUERY_BUFFER_SIZE];
  char index_value[STRING_BUFFER_USUAL_SIZE];
  char sql_query_buffer[FEDERATED_QUERY_BUFFER_SIZE];
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  String index_string(index_value,
2240 2241 2242 2243 2244 2245
                      sizeof(index_value),
                      &my_charset_bin);
  String sql_query(sql_query_buffer,
                   sizeof(sql_query_buffer),
                   &my_charset_bin);
  key_range range;
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  DBUG_ENTER("ha_federated::index_read_idx_with_result_set");
2247

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2248
  *result= 0;                                   // In case of errors
2249
  index_string.length(0);
2250
  sql_query.length(0);
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  statistic_increment(table->in_use->status_var.ha_read_key_count,
                      &LOCK_status);
2253 2254 2255

  sql_query.append(share->select_query);

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  range.key= key;
  range.length= key_len;
  range.flag= find_flag;
  create_where_from_key(&index_string,
                        &table->key_info[index],
                        &range,
2262
                        NULL, 0, 0);
2263 2264
  sql_query.append(index_string);

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  if (mysql_real_query(mysql, sql_query.ptr(), sql_query.length()))
2266
  {
2267
    my_sprintf(error_buffer, (error_buffer, "error: %d '%s'",
2268 2269
                              mysql_errno(mysql), mysql_error(mysql)));
    retval= ER_QUERY_ON_FOREIGN_DATA_SOURCE;
2270
    goto error;
2271
  }
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2272
  if (!(*result= mysql_store_result(mysql)))
2273
  {
2274 2275
    retval= HA_ERR_END_OF_FILE;
    goto error;
2276
  }
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2277 2278
  if (!(retval= read_next(buf, *result)))
    DBUG_RETURN(retval);
2279

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  mysql_free_result(*result);
  *result= 0;
  table->status= STATUS_NOT_FOUND;
2283
  DBUG_RETURN(retval);
2284

2285 2286 2287 2288
error:
  table->status= STATUS_NOT_FOUND;
  my_error(retval, MYF(0), error_buffer);
  DBUG_RETURN(retval);
2289 2290
}

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2291

2292
/* Initialized at each key walk (called multiple times unlike rnd_init()) */
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2293

2294
int ha_federated::index_init(uint keynr, bool sorted)
2295 2296
{
  DBUG_ENTER("ha_federated::index_init");
2297
  DBUG_PRINT("info", ("table: '%s'  key: %u", table->s->table_name.str, keynr));
2298 2299 2300 2301
  active_index= keynr;
  DBUG_RETURN(0);
}

2302

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2303 2304
/*
  Read first range
2305
*/
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2306

2307
int ha_federated::read_range_first(const key_range *start_key,
2308 2309
                                   const key_range *end_key,
                                   bool eq_range, bool sorted)
2310 2311 2312 2313 2314 2315 2316
{
  char sql_query_buffer[FEDERATED_QUERY_BUFFER_SIZE];
  int retval;
  String sql_query(sql_query_buffer,
                   sizeof(sql_query_buffer),
                   &my_charset_bin);
  DBUG_ENTER("ha_federated::read_range_first");
2317

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2318
  DBUG_ASSERT(!(start_key == NULL && end_key == NULL));
2319 2320 2321 2322 2323

  sql_query.length(0);
  sql_query.append(share->select_query);
  create_where_from_key(&sql_query,
                        &table->key_info[active_index],
2324
                        start_key, end_key, 0, eq_range);
2325

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  if (stored_result)
  {
    mysql_free_result(stored_result);
    stored_result= 0;
  }
2331 2332
  if (mysql_real_query(mysql, sql_query.ptr(), sql_query.length()))
  {
2333
    retval= ER_QUERY_ON_FOREIGN_DATA_SOURCE;
2334 2335 2336 2337
    goto error;
  }
  sql_query.length(0);

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2338
  if (!(stored_result= mysql_store_result(mysql)))
2339 2340 2341 2342 2343
  {
    retval= HA_ERR_END_OF_FILE;
    goto error;
  }

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2344
  retval= read_next(table->record[0], stored_result);
2345 2346 2347
  DBUG_RETURN(retval);

error:
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2348 2349
  table->status= STATUS_NOT_FOUND;
  DBUG_RETURN(retval);
2350 2351
}

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2352

2353 2354 2355 2356 2357 2358 2359 2360 2361
int ha_federated::read_range_next()
{
  int retval;
  DBUG_ENTER("ha_federated::read_range_next");
  retval= rnd_next(table->record[0]);
  DBUG_RETURN(retval);
}


2362
/* Used to read forward through the index.  */
2363
int ha_federated::index_next(byte *buf)
2364 2365
{
  DBUG_ENTER("ha_federated::index_next");
2366 2367
  statistic_increment(table->in_use->status_var.ha_read_next_count,
		      &LOCK_status);
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2368
  DBUG_RETURN(read_next(buf, stored_result));
2369
}
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2370 2371


2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383
/*
  rnd_init() is called when the system wants the storage engine to do a table
  scan.

  This is the method that gets data for the SELECT calls.

  See the federated in the introduction at the top of this file to see when
  rnd_init() is called.

  Called from filesort.cc, records.cc, sql_handler.cc, sql_select.cc,
  sql_table.cc, and sql_update.cc.
*/
2384

2385 2386
int ha_federated::rnd_init(bool scan)
{
2387
  DBUG_ENTER("ha_federated::rnd_init");
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2388
  /*
2389 2390 2391
    The use of the 'scan' flag is incredibly important for this handler
    to work properly, especially with updates containing WHERE clauses
    using indexed columns.
2392 2393 2394 2395 2396 2397 2398 2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 2420

    When the initial query contains a WHERE clause of the query using an
    indexed column, it's index_read_idx that selects the exact record from
    the foreign database.

    When there is NO index in the query, either due to not having a WHERE
    clause, or the WHERE clause is using columns that are not indexed, a
    'full table scan' done by rnd_init, which in this situation simply means
    a 'select * from ...' on the foreign table.

    In other words, this 'scan' flag gives us the means to ensure that if
    there is an index involved in the query, we want index_read_idx to
    retrieve the exact record (scan flag is 0), and do not  want rnd_init
    to do a 'full table scan' and wipe out that result set.

    Prior to using this flag, the problem was most apparent with updates.

    An initial query like 'UPDATE tablename SET anything = whatever WHERE
    indexedcol = someval', index_read_idx would get called, using a query
    constructed with a WHERE clause built from the values of index ('indexcol'
    in this case, having a value of 'someval').  mysql_store_result would
    then get called (this would be the result set we want to use).

    After this rnd_init (from sql_update.cc) would be called, it would then
    unecessarily call "select * from table" on the foreign table, then call
    mysql_store_result, which would wipe out the correct previous result set
    from the previous call of index_read_idx's that had the result set
    containing the correct record, hence update the wrong row!

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  */
2422

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2423
  if (scan)
2424
  {
2425
    if (stored_result)
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2426
    {
2427 2428
      mysql_free_result(stored_result);
      stored_result= 0;
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2429
    }
2430

2431 2432 2433 2434
    if (mysql_real_query(mysql,
                         share->select_query,
                         strlen(share->select_query)))
      goto error;
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2435

2436 2437
    stored_result= mysql_store_result(mysql);
    if (!stored_result)
2438
      goto error;
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2439
  }
2440
  DBUG_RETURN(0);
2441 2442

error:
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2443
  DBUG_RETURN(stash_remote_error());
2444 2445
}

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2446

2447 2448 2449
int ha_federated::rnd_end()
{
  DBUG_ENTER("ha_federated::rnd_end");
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2450
  DBUG_RETURN(index_end());
2451 2452
}

2453

2454 2455 2456
int ha_federated::index_end(void)
{
  DBUG_ENTER("ha_federated::index_end");
2457
  if (stored_result)
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2458
  {
2459 2460
    mysql_free_result(stored_result);
    stored_result= 0;
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2461
  }
2462 2463 2464 2465
  active_index= MAX_KEY;
  DBUG_RETURN(0);
}

2466

2467 2468 2469 2470 2471 2472 2473 2474 2475
/*
  This is called for each row of the table scan. When you run out of records
  you should return HA_ERR_END_OF_FILE. Fill buff up with the row information.
  The Field structure for the table is the key to getting data into buf
  in a manner that will allow the server to understand it.

  Called from filesort.cc, records.cc, sql_handler.cc, sql_select.cc,
  sql_table.cc, and sql_update.cc.
*/
2476

2477 2478 2479 2480
int ha_federated::rnd_next(byte *buf)
{
  DBUG_ENTER("ha_federated::rnd_next");

2481
  if (stored_result == 0)
2482 2483 2484 2485
  {
    /*
      Return value of rnd_init is not always checked (see records.cc),
      so we can get here _even_ if there is _no_ pre-fetched result-set!
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2486 2487
      TODO: fix it. We can delete this in 5.1 when rnd_init() is checked.
    */
2488 2489
    DBUG_RETURN(1);
  }
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2490 2491 2492 2493 2494 2495 2496 2497 2498 2499 2500 2501 2502 2503 2504 2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519 2520 2521
  DBUG_RETURN(read_next(buf, stored_result));
}


/*
  ha_federated::read_next

  reads from a result set and converts to mysql internal
  format

  SYNOPSIS
    field_in_record_is_null()
      buf       byte pointer to record 
      result    mysql result set 

    DESCRIPTION
     This method is a wrapper method that reads one record from a result
     set and converts it to the internal table format

    RETURN VALUE
      1    error
      0    no error 
*/

int ha_federated::read_next(byte *buf, MYSQL_RES *result)
{
  int retval;
  MYSQL_ROW row;
  DBUG_ENTER("ha_federated::read_next");

  table->status= STATUS_NOT_FOUND;              // For easier return

2522
  /* Fetch a row, insert it back in a row format. */
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2523
  if (!(row= mysql_fetch_row(result)))
2524
    DBUG_RETURN(HA_ERR_END_OF_FILE);
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2525

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2526 2527 2528
  if (!(retval= convert_row_to_internal_format(buf, row, result)))
    table->status= 0;

2529
  DBUG_RETURN(retval);
2530 2531 2532 2533
}


/*
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2534 2535
  store reference to current row so that we can later find it for
  a re-read, update or delete.
2536

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2537 2538
  In case of federated, a reference is either a primary key or
  the whole record.
2539 2540 2541

  Called from filesort.cc, sql_select.cc, sql_delete.cc and sql_update.cc.
*/
2542

2543 2544 2545
void ha_federated::position(const byte *record)
{
  DBUG_ENTER("ha_federated::position");
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2546 2547 2548 2549 2550
  if (table->s->primary_key != MAX_KEY)
    key_copy(ref, (byte *)record, table->key_info + table->s->primary_key,
             ref_length);
  else
    memcpy(ref, record, ref_length);
2551 2552 2553 2554 2555 2556
  DBUG_VOID_RETURN;
}


/*
  This is like rnd_next, but you are given a position to use to determine the
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2557
  row. The position will be of the type that you stored in ref.
2558

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2559
  This method is required for an ORDER BY
2560 2561 2562

  Called from filesort.cc records.cc sql_insert.cc sql_select.cc sql_update.cc.
*/
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2563

2564
int ha_federated::rnd_pos(byte *buf, byte *pos)
2565
{
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2566
  int result;
2567
  DBUG_ENTER("ha_federated::rnd_pos");
2568 2569
  statistic_increment(table->in_use->status_var.ha_read_rnd_count,
                      &LOCK_status);
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2570 2571 2572 2573 2574 2575 2576 2577 2578 2579 2580 2581 2582 2583
  if (table->s->primary_key != MAX_KEY)
  {
    /* We have a primary key, so use index_read_idx to find row */
    result= index_read_idx(buf, table->s->primary_key, pos,
                           ref_length, HA_READ_KEY_EXACT);
  }
  else
  {
    /* otherwise, get the old record ref as obtained in ::position */
    memcpy(buf, pos, ref_length);
    result= 0;
  }
  table->status= result ? STATUS_NOT_FOUND : 0;
  DBUG_RETURN(result);
2584 2585 2586 2587 2588 2589 2590 2591 2592 2593 2594 2595 2596 2597 2598 2599 2600 2601 2602 2603 2604 2605 2606 2607 2608 2609 2610 2611 2612 2613 2614 2615 2616 2617 2618 2619 2620 2621 2622 2623 2624 2625 2626 2627 2628 2629
}


/*
  ::info() is used to return information to the optimizer.
  Currently this table handler doesn't implement most of the fields
  really needed. SHOW also makes use of this data
  Another note, you will probably want to have the following in your
  code:
  if (records < 2)
    records = 2;
  The reason is that the server will optimize for cases of only a single
  record. If in a table scan you don't know the number of records
  it will probably be better to set records to two so you can return
  as many records as you need.
  Along with records a few more variables you may wish to set are:
    records
    deleted
    data_file_length
    index_file_length
    delete_length
    check_time
  Take a look at the public variables in handler.h for more information.

  Called in:
    filesort.cc
    ha_heap.cc
    item_sum.cc
    opt_sum.cc
    sql_delete.cc
    sql_delete.cc
    sql_derived.cc
    sql_select.cc
    sql_select.cc
    sql_select.cc
    sql_select.cc
    sql_select.cc
    sql_show.cc
    sql_show.cc
    sql_show.cc
    sql_show.cc
    sql_table.cc
    sql_union.cc
    sql_update.cc

*/
2630

2631
int ha_federated::info(uint flag)
2632
{
2633 2634 2635 2636 2637
  char error_buffer[FEDERATED_QUERY_BUFFER_SIZE];
  char status_buf[FEDERATED_QUERY_BUFFER_SIZE];
  char escaped_table_name[FEDERATED_QUERY_BUFFER_SIZE];
  int error;
  uint error_code;
2638
  MYSQL_RES *result= 0;
2639 2640
  MYSQL_ROW row;
  String status_query_string(status_buf, sizeof(status_buf), &my_charset_bin);
2641
  DBUG_ENTER("ha_federated::info");
2642

2643
  error_code= ER_QUERY_ON_FOREIGN_DATA_SOURCE;
2644 2645 2646 2647
  /* we want not to show table status if not needed to do so */
  if (flag & (HA_STATUS_VARIABLE | HA_STATUS_CONST))
  {
    status_query_string.length(0);
2648
    status_query_string.append(STRING_WITH_LEN("SHOW TABLE STATUS LIKE '"));
2649 2650 2651 2652 2653
    escape_string_for_mysql(&my_charset_bin, (char *)escaped_table_name,
                            sizeof(escaped_table_name),
                            share->table_name,
                            share->table_name_length);
    status_query_string.append(escaped_table_name);
2654
    status_query_string.append(STRING_WITH_LEN("'"));
2655 2656 2657 2658 2659 2660 2661 2662

    if (mysql_real_query(mysql, status_query_string.ptr(),
                         status_query_string.length()))
      goto error;

    status_query_string.length(0);

    result= mysql_store_result(mysql);
2663
    if (!result)
2664 2665
      goto error;

2666
    if (!mysql_num_rows(result))
2667 2668 2669 2670 2671 2672 2673
      goto error;

    if (!(row= mysql_fetch_row(result)))
      goto error;

    if (flag & HA_STATUS_VARIABLE | HA_STATUS_CONST)
    {
2674
      /*
2675 2676 2677 2678 2679 2680 2681 2682 2683 2684 2685
        deleted is set in ha_federated::info
      */
      /*
        need to figure out what this means as far as federated is concerned,
        since we don't have a "file"

        data_file_length = ?
        index_file_length = ?
        delete_length = ?
      */
      if (row[4] != NULL)
2686
        stats.records=   (ha_rows) my_strtoll10(row[4], (char**) 0,
2687
                                                       &error);
2688
      if (row[5] != NULL)
2689
        stats.mean_rec_length= (ha_rows) my_strtoll10(row[5], (char**) 0, &error);
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2690

2691
      stats.data_file_length= stats.records * stats.mean_rec_length;
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2692

2693
      if (row[12] != NULL)
2694 2695
        stats.update_time=     (ha_rows) my_strtoll10(row[12], (char**) 0,
                                                      &error);
2696
      if (row[13] != NULL)
2697 2698
        stats.check_time=      (ha_rows) my_strtoll10(row[13], (char**) 0,
                                                      &error);
2699
    }
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2700 2701 2702 2703
    /*
      size of IO operations (This is based on a good guess, no high science
      involved)
    */
2704
    if (flag & HA_STATUS_CONST)
2705
      stats.block_size= 4096;
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2706

2707 2708 2709 2710
  }

  if (result)
    mysql_free_result(result);
2711

2712
  DBUG_RETURN(0);
2713 2714 2715 2716

error:
  if (result)
    mysql_free_result(result);
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2717

2718 2719
  my_sprintf(error_buffer, (error_buffer, ": %d : %s",
                            mysql_errno(mysql), mysql_error(mysql)));
2720
  my_error(error_code, MYF(0), error_buffer);
2721
  DBUG_RETURN(error_code);
2722 2723 2724 2725 2726 2727 2728 2729 2730 2731 2732 2733 2734 2735
}


/*
  Used to delete all rows in a table. Both for cases of truncate and
  for cases where the optimizer realizes that all rows will be
  removed as a result of a SQL statement.

  Called from item_sum.cc by Item_func_group_concat::clear(),
  Item_sum_count_distinct::clear(), and Item_func_group_concat::clear().
  Called from sql_delete.cc by mysql_delete().
  Called from sql_select.cc by JOIN::reinit().
  Called from sql_union.cc by st_select_lex_unit::exec().
*/
2736

2737 2738
int ha_federated::delete_all_rows()
{
2739
  char query_buffer[FEDERATED_QUERY_BUFFER_SIZE];
2740
  String query(query_buffer, sizeof(query_buffer), &my_charset_bin);
2741 2742
  DBUG_ENTER("ha_federated::delete_all_rows");

2743 2744 2745
  query.length(0);

  query.set_charset(system_charset_info);
2746
  query.append(STRING_WITH_LEN("TRUNCATE `"));
2747
  query.append(share->table_name);
2748
  query.append(STRING_WITH_LEN("`"));
2749

2750 2751 2752
  /*
    TRUNCATE won't return anything in mysql_affected_rows
  */
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2753 2754
  if (mysql_real_query(mysql, query.ptr(), query.length()))
  {
2755
    DBUG_RETURN(stash_remote_error());
2756
  }
2757 2758
  stats.deleted+= stats.records;
  stats.records= 0;
2759
  DBUG_RETURN(0);
2760 2761 2762 2763 2764 2765 2766 2767 2768 2769 2770 2771 2772 2773 2774 2775 2776 2777 2778 2779 2780 2781 2782 2783 2784 2785 2786 2787 2788 2789 2790 2791
}


/*
  The idea with handler::store_lock() is the following:

  The statement decided which locks we should need for the table
  for updates/deletes/inserts we get WRITE locks, for SELECT... we get
  read locks.

  Before adding the lock into the table lock handler (see thr_lock.c)
  mysqld calls store lock with the requested locks.  Store lock can now
  modify a write lock to a read lock (or some other lock), ignore the
  lock (if we don't want to use MySQL table locks at all) or add locks
  for many tables (like we do when we are using a MERGE handler).

  Berkeley DB for federated  changes all WRITE locks to TL_WRITE_ALLOW_WRITE
  (which signals that we are doing WRITES, but we are still allowing other
  reader's and writer's.

  When releasing locks, store_lock() are also called. In this case one
  usually doesn't have to do anything.

  In some exceptional cases MySQL may send a request for a TL_IGNORE;
  This means that we are requesting the same lock as last time and this
  should also be ignored. (This may happen when someone does a flush
  table when we have opened a part of the tables, in which case mysqld
  closes and reopens the tables and tries to get the same locks at last
  time).  In the future we will probably try to remove this.

  Called from lock.cc by get_lock_data().
*/
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THR_LOCK_DATA **ha_federated::store_lock(THD *thd,
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                                         THR_LOCK_DATA **to,
                                         enum thr_lock_type lock_type)
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{
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  DBUG_ENTER("ha_federated::store_lock");
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  if (lock_type != TL_IGNORE && lock.type == TL_UNLOCK)
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  {
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    /*
      Here is where we get into the guts of a row level lock.
      If TL_UNLOCK is set
      If we are not doing a LOCK TABLE or DISCARD/IMPORT
      TABLESPACE, then allow multiple writers
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    */

    if ((lock_type >= TL_WRITE_CONCURRENT_INSERT &&
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         lock_type <= TL_WRITE) && !thd->in_lock_tables)
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      lock_type= TL_WRITE_ALLOW_WRITE;

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    /*
      In queries of type INSERT INTO t1 SELECT ... FROM t2 ...
      MySQL would use the lock TL_READ_NO_INSERT on t2, and that
      would conflict with TL_WRITE_ALLOW_WRITE, blocking all inserts
      to t2. Convert the lock to a normal read lock to allow
      concurrent inserts to t2.
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    */

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    if (lock_type == TL_READ_NO_INSERT && !thd->in_lock_tables)
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      lock_type= TL_READ;

    lock.type= lock_type;
  }

  *to++= &lock;

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  DBUG_RETURN(to);
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}

/*
  create() does nothing, since we have no local setup of our own.
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  FUTURE: We should potentially connect to the foreign database and
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*/
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int ha_federated::create(const char *name, TABLE *table_arg,
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                         HA_CREATE_INFO *create_info)
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{
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  int retval;
  FEDERATED_SHARE tmp_share; // Only a temporary share, to test the url
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  DBUG_ENTER("ha_federated::create");
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  if (!(retval= parse_url(&tmp_share, table_arg, 1)))
    retval= check_foreign_data_source(&tmp_share, 1);
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  /* free this because strdup created it in parse_url */
  my_free((gptr) tmp_share.connection_string, MYF(MY_ALLOW_ZERO_PTR));
  tmp_share.connection_string= 0;
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  DBUG_RETURN(retval);
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}
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int ha_federated::stash_remote_error()
{
  DBUG_ENTER("ha_federated::stash_remote_error()");
  remote_error_number= mysql_errno(mysql);
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  strmake(remote_error_buf, mysql_error(mysql), sizeof(remote_error_buf)-1);
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  DBUG_RETURN(HA_FEDERATED_ERROR_WITH_REMOTE_SYSTEM);
}


bool ha_federated::get_error_message(int error, String* buf)
{
  DBUG_ENTER("ha_federated::get_error_message");
  DBUG_PRINT("enter", ("error: %d", error));
  if (error == HA_FEDERATED_ERROR_WITH_REMOTE_SYSTEM)
  {
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    buf->append(STRING_WITH_LEN("Error on remote system: "));
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    buf->qs_append(remote_error_number);
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    buf->append(STRING_WITH_LEN(": "));
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    buf->append(remote_error_buf);
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    remote_error_number= 0;
    remote_error_buf[0]= '\0';
  }
  DBUG_PRINT("exit", ("message: %s", buf->ptr()));
  DBUG_RETURN(FALSE);
}

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int ha_federated::external_lock(THD *thd, int lock_type)
{
  int error= 0;
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  ha_federated *trx= (ha_federated *)thd->ha_data[ht->slot];
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  DBUG_ENTER("ha_federated::external_lock");

  if (lock_type != F_UNLCK)
  {
    DBUG_PRINT("info",("federated not lock F_UNLCK"));
    if (!(thd->options & (OPTION_NOT_AUTOCOMMIT | OPTION_BEGIN))) 
    {
      DBUG_PRINT("info",("federated autocommit"));
      /* 
        This means we are doing an autocommit
      */
      error= connection_autocommit(TRUE);
      if (error)
      {
        DBUG_PRINT("info", ("error setting autocommit TRUE: %d", error));
        DBUG_RETURN(error);
      }
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      trans_register_ha(thd, FALSE, ht);
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    }
    else 
    { 
      DBUG_PRINT("info",("not autocommit"));
      if (!trx)
      {
        /* 
          This is where a transaction gets its start
        */
        error= connection_autocommit(FALSE);
        if (error)
        { 
          DBUG_PRINT("info", ("error setting autocommit FALSE: %d", error));
          DBUG_RETURN(error);
        }
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        thd->ha_data[ht->slot]= this;
        trans_register_ha(thd, TRUE, ht);
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        /*
          Send a lock table to the remote end.
          We do not support this at the moment
        */
        if (thd->options & (OPTION_TABLE_LOCK))
        {
          DBUG_PRINT("info", ("We do not support lock table yet"));
        }
      }
      else
      {
        ha_federated *ptr;
        for (ptr= trx; ptr; ptr= ptr->trx_next)
          if (ptr == this)
            break;
          else if (!ptr->trx_next)
            ptr->trx_next= this;
      }
    }
  }
  DBUG_RETURN(0);
}


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static int federated_commit(handlerton *hton, THD *thd, bool all)
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{
  int return_val= 0;
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  ha_federated *trx= (ha_federated *)thd->ha_data[hton->slot];
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  DBUG_ENTER("federated_commit");

  if (all)
  {
    int error= 0;
    ha_federated *ptr, *old= NULL;
    for (ptr= trx; ptr; old= ptr, ptr= ptr->trx_next)
    {
      if (old)
        old->trx_next= NULL;
      error= ptr->connection_commit();
      if (error && !return_val);
        return_val= error;
    }
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    thd->ha_data[hton->slot]= NULL;
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  }

  DBUG_PRINT("info", ("error val: %d", return_val));
  DBUG_RETURN(return_val);
}


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static int federated_rollback(handlerton *hton, THD *thd, bool all)
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{
  int return_val= 0;
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  ha_federated *trx= (ha_federated *)thd->ha_data[hton->slot];
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  DBUG_ENTER("federated_rollback");

  if (all)
  {
    int error= 0;
    ha_federated *ptr, *old= NULL;
    for (ptr= trx; ptr; old= ptr, ptr= ptr->trx_next)
    {
      if (old)
        old->trx_next= NULL;
      error= ptr->connection_rollback();
      if (error && !return_val)
        return_val= error;
    }
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    thd->ha_data[hton->slot]= NULL;
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  }

  DBUG_PRINT("info", ("error val: %d", return_val));
  DBUG_RETURN(return_val);
}

int ha_federated::connection_commit()
{
  DBUG_ENTER("ha_federated::connection_commit");
  DBUG_RETURN(execute_simple_query("COMMIT", 6));
}


int ha_federated::connection_rollback()
{
  DBUG_ENTER("ha_federated::connection_rollback");
  DBUG_RETURN(execute_simple_query("ROLLBACK", 8));
}


int ha_federated::connection_autocommit(bool state)
{
  const char *text;
  DBUG_ENTER("ha_federated::connection_autocommit");
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  text= (state == TRUE) ? "SET AUTOCOMMIT=1" : "SET AUTOCOMMIT=0";
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  DBUG_RETURN(execute_simple_query(text, 16));
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}
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int ha_federated::execute_simple_query(const char *query, int len)
{
  DBUG_ENTER("ha_federated::execute_simple_query");

  if (mysql_real_query(mysql, query, len))
  {
    DBUG_RETURN(stash_remote_error());
  }
  DBUG_RETURN(0);
}

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struct st_mysql_storage_engine federated_storage_engine=
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{ MYSQL_HANDLERTON_INTERFACE_VERSION };
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mysql_declare_plugin(federated)
{
  MYSQL_STORAGE_ENGINE_PLUGIN,
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  &federated_storage_engine,
  "FEDERATED",
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  "Patrick Galbraith and Brian Aker, MySQL AB",
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  "Federated MySQL storage engine",
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  PLUGIN_LICENSE_GPL,
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  federated_db_init, /* Plugin Init */
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  federated_done, /* Plugin Deinit */
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  0x0100 /* 1.0 */,
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  NULL,                       /* status variables                */
  NULL,                       /* system variables                */
  NULL                        /* config options                  */
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}
mysql_declare_plugin_end;