Updated code comments according to reviewers requests.

                           PARTITION STATISTICS

Problem was the fix for bug#11756867; It always used the first
partitions, and stopped after it checked 10 [sub]partitions.
(or until it found a partition which would contain a match).

This results in bad statistics for tables where the first 10 partitions
don't represent the majority of the data (like when the first 10
partitions only contained a few rows in total).

The solution was to take statisics from the partitions containing
the most rows instead:

Added an array of partition ids which is sorted by number of records
in descending order.

this array is used in records_in_range to cover as many records as
possible in as few calls as possible.

Also changed the limit of how many partitions to use for the statistics
from a static max of 10 partitions, into a dynamic model:
Maximum number of partitions is now log2(total number of partitions)
taken from the ordered array.
It will continue calling partitions records_in_range until it has 
checked:
(total rows in matching partitions) * (maximum number of partitions)
/ (number of used partitions)

Also reverted the changes for ha_partition::scan_time() and
ha_partition::estimate_rows_upper_bound() to before
the fix of  bug#11756867. Since they are not as slow as
records_in_range.

            
During FIC error handling the trx->error_state was not being set to DB_SUCCESS
after failure, before attempting the next DDL SQL operation. This reset to
DB_SUCCESS is somewhat of a requirement though not explicitly stated anywhere.
The fix is to reset it to DB_SUCCESS in row0merge.cc if row_merge_rename_indexes
or row_merge_drop_index functions fail, also reset to DB_SUCCESS at trx commit.
				          
rb://935 Approved by Jimmy Yang.

GRACEFUL SHUTDOWN

During startup mysql picks up .frm files from the tmpdir directory and
tries to drop those tables in the storage engine.

The problem is that when tmpdir ends in / then ha_innobase::delete_table()
is passed a string like "/var/tmp//#sql123", then it wrongly normalizes it
to "/#sql123" and calls row_drop_table_for_mysql() which of course fails
to delete the table entry from the InnoDB dictionary cache.
ha_innobase::delete_table() returns an error but nevertheless mysql wipes
away the .frm file and the entry in the InnoDB dictionary cache remains
orphaned with no easy way to remove it.

The "no easy" way to remove it is to create a similar temporary table again,
copy its .frm file to tmpdir under "#sql123.frm" and restart mysqld with
tmpdir=/var/tmp (no trailing slash) - this way mysql will pick the .frm file
after restart and will try to issue drop table for "/var/tmp/#sql123"
(notice do double slash), ha_innobase::delete_table() will normalize it to
"tmp/#sql123" and row_drop_table_for_mysql() will successfully remove the
table entry from the dictionary cache.

The solution is to fix normalize_table_name_low() to normalize things like
"/var/tmp//table" correctly to "tmp/table".

This patch also adds a test function which invokes
normalize_table_name_low() with various inputs to make sure it works
correctly and a mtr test that calls this test function.

Reviewed by:	Marko (http://bur03.no.oracle.com/rb/r/929/)

                      CORRUPTED WHEN RUN CONCURRENTLY WITH

ISSUE: Table corruption due to concurrent queries.
       Different threads running check, repair query
       along with insert. Locks not properly acquired
       in repair query. Rows are inserted inbetween
       repair query.

SOLUTION: Mutex lock is acquired before the
          repair call. Concurrent queries wont
          effect the call to repair.

Recording correct test results.

modified:
  mysql-test/suite/engines/funcs/r/db_alter_collate_ascii.result
  mysql-test/suite/engines/funcs/r/db_alter_collate_utf8.result

row_merge_buf_write(): Relax the bogus assertion.

                      CASES RESETS DATA POINTER TO SMAL

ISSUE: Myisamchk doing sort recover
       on a table reduces data_file_length.
       Maximum size of data file decreases,
       lesser number of rows are stored.

SOLUTION: Size of data_file_length is
          fixed to the original length.

                      CASES RESETS DATA POINTER TO SMAL

ISSUE: Myisamchk doing sort recover
       on a table reduces data_file_length.
       Maximum size of data file decreases,
       lesser number of rows are stored.

SOLUTION: Size of data_file_length is
          fixed to the original length.

rb://914
approved by: Marko Makela

Poll in fil_rename_tablespace() after setting ::stop_ios flag can
result in a hang because the other thread actually dispatching the IO
won't wake IO helper threads or flush the tablespace before starting
wait in fil_mutex_enter_and_prepare_for_io().

No commit message

Fix for #36428/#38364 backported into 5.0.

BUG#13519696 - 62940: SELECT RESULTS VARY WITH VERSION AND
WITH/WITHOUT INDEX RANGE SCAN
BUG#13453382 - REGRESSION SINCE 5.1.39, RANGE OPTIMIZER WRONG
RESULTS WITH DECIMAL CONVERSION
BUG#13463488 - 63437: CHAR & BETWEEN WITH INDEX RETURNS WRONG
RESULT AFTER MYSQL 5.1.
Those are all cases where the range optimizer got it wrong
with > and >=.

and some Valgrind instrumentation.

- Reverting the patch for Bug # 12584302
  The patch will be reverted in 5.1 and 5.5.
  The patch will not be reverted in 5.6, the change will
  be properly documented in 5.6.
- Backporting DBUG_ASSERT not to crash on '0000-01-00'
  (already fixed in mysql-trunk (5.6))

Introducing new collations:
utf8_general_mysql500_ci and ucs2_general_mysql500_ci,
to reproduce behaviour of utf8_general_ci and ucs2_general_ci
from mysql-5.1.23 (and earlier).

The collations are added to simplify upgrade from mysql-5.1.23 and earlier.

Note: The patch does not make new server start over old data automatically.
Some manual upgrade procedures are assumed.

Paul: please get in touch with me to discuss upgrade procedures
when documenting this bug.

modified:
  include/m_ctype.h
  mysql-test/r/ctype_utf8.result
  mysql-test/t/ctype_utf8.test
  mysys/charset-def.c
  strings/ctype-ucs2.c
  strings/ctype-utf8.c

                     DUMP ROUTINES

Minor post-fix to avoid build failure when built with
Werror.

Relax a bogus debug assertion.
Approved by Jimmy Yang on IM.

Test extra/rpl_tests/rpl_extra_col_master.test (used by
rpl_extra_col_master_*) ends with the active connection pointing to the
slave. Thus, the two last tests never succeed in changing the binlog
format of the master away from 'row'. With correct active connection
(master) tests fail for binlog 'statement' and 'mixed' formats.

Tests rpl_extra_col_master_* only run when binary log format is
row.  Statement and mix replication do not make sense in this
tests since it will try to execute statements on columns that do
not exist.  This fix is basically a backport from mysql-5.5, see
changes done as part of BUG 39934.

When mode==BUF_KEEP_OLD, buffered inserts are being merged to the page.
It is possible that a read request for a page was pending while the page
was freed in DROP INDEX or DROP TABLE. In these cases, it is OK (although
useless) to merge the buffered changes to the freed page.

ISSUES WITH COPYING PARTITIONED INNODB TABLES FROM LINUX TO WINDOWS

This problem was already fixed in mysql-trunk as part of bug #11755924.  I am 
backporting the fix to mysql-5.1.  

                     routines.

mysqldump in xml mode did not dump routines, events or
triggers.

This patch fixes this issue by fixing the if conditions
that disallowed the dump of above mentioned objects in
xml mode, and added the required code to enable dump
in xml format.

If we meet DB_TOO_MANY_CONCURRENT_TRXS during the execution tab_create_graph from row_create_table_for_mysql(), .ibd file for the table should be created already but was not deleted for the error handling.

rb:875 approved by Jimmy Yang

Fixed it to work with "--repeat" option.

Fixed the testcase using timestamp logic while doing grep from the error file.

If init_command was incorrect, we couldn't let users execute
queries, but we couldn't report the issue to the client either
as it does not expect error messages before even sending a
command. Thus, we simply disconnected them without throwing
a clear error.

We now go through the proper sequence once (without executing
any user statements) so we can report back what the problem
is. Only then do we disconnect the user.

As always, root remains unaffected by this as init_command is
(still) not executed for them.

InnoDB: Remove HAVE_purify, UNIV_INIT_MEM_TO_ZERO, UNIV_SET_MEM_TO_ZERO.

The compile-time setting HAVE_purify can mask potential bugs.
It is being set in PB2 Valgrind runs. We should simply get rid of it,
and replace it with UNIV_MEM_INVALID() to declare uninitialized memory
as such in Valgrind-instrumented binaries.

os_mem_alloc_large(), ut_malloc_low(): Remove the parameter set_to_zero.

ut_malloc(): Define as a macro that invokes ut_malloc_low().

buf_pool_init(): Never initialize the buffer pool frames. All pages
must be initialized before flushing them to disk.

mem_heap_alloc(): Never initialize the allocated memory block.

os_mem_alloc_nocache(), ut_test_malloc(): Unused function, remove.

rb:813 approved by Jimmy Yang

COMMUNICATION PACKETS, ERROR_CODE: 1160

Addendum: for some queries table->in_use might be NULL -
check it.

COMMUNICATION PACKETS, ERROR_CODE: 1160

If idle FEDERATED table is evicted from the table cache when 
a connection to remote server is lost, query that initiated 
eviction may fail.
If this query is executed by slave SQL thread it may fail as well.

An error of close was stored in diagnostics area, which was later
attributed to the statement that caused eviction.

With this patch FEDERATED clears an error of close.

rb://865
approved by: Jimmy

Integer overflow causes division by zero.