corrupts a MERGE table
Bug 26867 - LOCK TABLES + REPAIR + merge table result in
            memory/cpu hogging
Bug 26377 - Deadlock with MERGE and FLUSH TABLE
Bug 25038 - Waiting TRUNCATE
Bug 25700 - merge base tables get corrupted by
            optimize/analyze/repair table
Bug 30275 - Merge tables: flush tables or unlock tables
            causes server to crash
Bug 19627 - temporary merge table locking
Bug 27660 - Falcon: merge table possible
Bug 30273 - merge tables: Can't lock file (errno: 155)

The problems were:

Bug 26379 - Combination of FLUSH TABLE and REPAIR TABLE
                corrupts a MERGE table

  1. A thread trying to lock a MERGE table performs busy waiting while
     REPAIR TABLE or a similar table administration task is ongoing on
     one or more of its MyISAM tables.
  
  2. A thread trying to lock a MERGE table performs busy waiting until all
     threads that did REPAIR TABLE or similar table administration tasks
     on one or more of its MyISAM tables in LOCK TABLES segments do UNLOCK
     TABLES. The difference against problem #1 is that the busy waiting
     takes place *after* the administration task. It is terminated by
     UNLOCK TABLES only.
  
  3. Two FLUSH TABLES within a LOCK TABLES segment can invalidate the
     lock. This does *not* require a MERGE table. The first FLUSH TABLES
     can be replaced by any statement that requires other threads to
     reopen the table. In 5.0 and 5.1 a single FLUSH TABLES can provoke
     the problem.

Bug 26867 - LOCK TABLES + REPAIR + merge table result in
            memory/cpu hogging

  Trying DML on a MERGE table, which has a child locked and
  repaired by another thread, made an infinite loop in the server.

Bug 26377 - Deadlock with MERGE and FLUSH TABLE

  Locking a MERGE table and its children in parent-child order
  and flushing the child deadlocked the server.

Bug 25038 - Waiting TRUNCATE

  Truncating a MERGE child, while the MERGE table was in use,
  let the truncate fail instead of waiting for the table to
  become free.

Bug 25700 - merge base tables get corrupted by
            optimize/analyze/repair table

  Repairing a child of an open MERGE table corrupted the child.
  It was necessary to FLUSH the child first.

Bug 30275 - Merge tables: flush tables or unlock tables
            causes server to crash

  Flushing and optimizing locked MERGE children crashed the server.

Bug 19627 - temporary merge table locking

  Use of a temporary MERGE table with non-temporary children
  could corrupt the children.

  Temporary tables are never locked. So we do now prohibit
  non-temporary chidlren of a temporary MERGE table.

Bug 27660 - Falcon: merge table possible

  It was possible to create a MERGE table with non-MyISAM children.

Bug 30273 - merge tables: Can't lock file (errno: 155)

  This was a Windows-only bug. Table administration statements
  sometimes failed with "Can't lock file (errno: 155)".

These bugs are fixed by a new implementation of MERGE table open.

When opening a MERGE table in open_tables() we do now add the
child tables to the list of tables to be opened by open_tables()
(the "query_list"). The children are not opened in the handler at
this stage.

After opening the parent, open_tables() opens each child from the
now extended query_list. When the last child is opened, we remove
the children from the query_list again and attach the children to
the parent. This behaves similar to the old open. However it does
not open the MyISAM tables directly, but grabs them from the already
open children.

When closing a MERGE table in close_thread_table() we detach the
children only. Closing of the children is done implicitly because
they are in thd->open_tables.

For more detail see the comment at the top of ha_myisammrg.cc.

Changed from open_ltable() to open_and_lock_tables() in all places
that can be relevant for MERGE tables. The latter can handle tables
added to the list on the fly. When open_ltable() was used in a loop
over a list of tables, the list must be temporarily terminated
after every table for open_and_lock_tables().
table_list->required_type is set to FRMTYPE_TABLE to avoid open of
special tables. Handling of derived tables is suppressed.
These details are handled by the new function
open_n_lock_single_table(), which has nearly the same signature as
open_ltable() and can replace it in most cases.

In reopen_tables() some of the tables open by a thread can be
closed and reopened. When a MERGE child is affected, the parent
must be closed and reopened too. Closing of the parent is forced
before the first child is closed. Reopen happens in the order of
thd->open_tables. MERGE parents do not attach their children
automatically at open. This is done after all tables are reopened.
So all children are open when attaching them.

Special lock handling like mysql_lock_abort() or mysql_lock_remove()
needs to be suppressed for MERGE children or forwarded to the parent.
This depends on the situation. In loops over all open tables one
suppresses child lock handling. When a single table is touched,
forwarding is done.

Behavioral changes:
===================

This patch changes the behavior of temporary MERGE tables.
Temporary MERGE must have temporary children.
The old behavior was wrong. A temporary table is not locked. Hence
even non-temporary children were not locked. See
Bug 19627 - temporary merge table locking.

You cannot change the union list of a non-temporary MERGE table
when LOCK TABLES is in effect. The following does *not* work:
CREATE TABLE m1 ... ENGINE=MRG_MYISAM ...;
LOCK TABLES t1 WRITE, t2 WRITE, m1 WRITE;
ALTER TABLE m1 ... UNION=(t1,t2) ...;
However, you can do this with a temporary MERGE table.

You cannot create a MERGE table with CREATE ... SELECT, neither
as a temporary MERGE table, nor as a non-temporary MERGE table.
CREATE TABLE m1 ... ENGINE=MRG_MYISAM ... SELECT ...;
Gives error message: table is not BASE TABLE.

            the wrong buffer
Post-pushbuild fix
Added test case for better coverage.

into  stella.local:/home2/mydev/mysql-5.1-bug4692

into  stella.local:/home2/mydev/mysql-5.1-bug4692

into  stella.local:/home2/mydev/mysql-5.0-bug4692

into  stella.local:/home2/mydev/mysql-5.1-bug4692

Post-pushbuild fix

Added a purecov comment and a test for coverage of parallel
enable keys.

into  mysql.com:/home/svoj/devel/mysql/BUG31277/mysql-5.1-engines

into  mysql.com:/home/svoj/devel/mysql/BUG31277/mysql-5.0-engines

into  mysql.com:/home/svoj/devel/mysql/BUG31277/mysql-4.1-engines

into  mysql.com:/home/svoj/devel/mysql/BUG31277/mysql-4.1-engines

Post pushbuild fix

Disabled test on windows due to bug#30459
(DATA/INDEX DIR for partitions not working on windows)

Patch from Mattias Jonsson.

into  stella.local:/home2/mydev/mysql-5.1-bug31210

            if running as root

Every start of a server in the test suite raised that warning.

The cause was an unconditionla add of the --user option to the
server command line. Only the "root" user (effective user id == 0)
must use that option.

Added check for effective user id == 0 before adding --user.

Thanks to Magnus Svensson for the patch.

into  mattiasj-laptop.(none):/home/mattiasj/clones/mysql-5.0-engines_with_main

into  mattiasj-laptop.(none):/home/mattiasj/clones/mysql-5.1-last_with_main

into  mattiasj-laptop.(none):/home/mattiasj/clones/mysql-5.0-engines_with_main

into  mattiasj-laptop.(none):/home/mattiasj/clones/mysql-5.1-last_with_main

into  mysql.com:/home/svoj/devel/mysql/BUG32111/mysql-5.1-engines

into  mysql.com:/home/svoj/devel/mysql/BUG32111/mysql-5.0-engines

  Use proper variable for test.

into  stella.local:/home2/mydev/mysql-5.1-bug31210

into  mattiasj-laptop.(none):/home/mattiasj/clones/mysql-5.1-lastfinaltopush

into  mattiasj-laptop.(none):/home/mattiasj/clones/mysql-5.1-lastfinaltopush

into  mattiasj-laptop.(none):/home/mattiasj/clones/mysql-5.1-lastfinaltopush

into  mattiasj-laptop.(none):/home/mattiasj/clones/mysql-5.1-lastfinaltopush

Buffer overflow due to wrong key length in partitioning

Changed to the correct key_length function.

Merge fix

partition_mgm did not require have_symlink.

Moved the test case to partition_symlink, which
require have_symlink, and should work on both *nix and
Windows

                partitioned table
    
Post-pushbuild fix
    
Pushbuild detected yet another need for lex initialization in
embedded server.

into  mysql.com:/home/svoj/devel/mysql/BUG32111/mysql-5.1-engines

into  mysql.com:/home/svoj/devel/mysql/BUG32111/mysql-5.0-engines

into  mysql.com:/home/svoj/devel/mysql/BUG32111/mysql-4.1-engines

Adding missing drop of user created for test case.

    causes the Server to crash.

Post-pushbuild fix

Pushbuild genereted valgrind warnings.

Changed function to safer variant.

              partitioned table
  
Post-pushbuild fix
  
Pushbuild detected a new need for lex initialization in
embedded server.

Fixed test for INSERT DELAYED in partitions_hash.test so that
it works with embedded server.

Changed test case from GRANT to CREATE USER

small fix of test case (when running make test after
merge, it did not substitute MYSQLTEST_VARDIR in
the error)

            partitioned table

Post-merge fix

A new need for lex initialization arose.

Problem: there was no standard syntax error when
         creating partitions with syntax error in
         the partitioning clause.

Solution: added "Syntax error: " to the error message