Some changes that make things more elegant in 6.0,
backported so the code is mostly the same in 5.1,
for easier maintainence.

The problem was that the server was trying to use the unknown
error format string (ER_UNKNOWN_ERROR) to print messages about
comments being too long, but the said format string does not
accept arguments and will always default to "Unknown error".

The solution is to introduce new error messages which are
specific to the error conditions so that server wants to
signal -- this also means that it's possible to translate
those messages.

                          
When using mixed mode the record values stored inside the storage
engine differed from the ones computed from the row event. This
happened because the prepare_record function was calling
empty_record macro causing some don't care bits to be left set.
                          
Replacing the empty_record plus explicitly setting defaults with 
restore_record to restore the record default values fixes this.                          

An unnecessarily restrictive lock were taken on sub-SELECTs during DELETE.

During parsing, a global structure is reused for sub-SELECTs and the attribute
keeping track of lock options were not reset properly.
This patch introduces a new attribute to keep track on the syntactical lock
option elements found in a sub-SELECT and then sets the lock options accordingly.

Now the sub-SELECTs will try to acquire a READ lock if possible
instead of a WRITE lock as inherited from the outer DELETE statement.

This is a back port from 5.1 to 5.0.

Fix for BUG 20023: mysql_change_user() resets the value
of SQL_BIG_SELECTS.
  
The bug was that SQL_BIG_SELECTS was not properly set
in COM_CHANGE_USER.
  
The fix is to update SQL_BIG_SELECTS properly.

      
When binlog_format is STATEMENT and the statement is unsafe before,
the unsafe warning/error message was issued without checking
whether the SQL_LOG_BIN was turned on or not.
      
Fixed with adding a sql_log_bin_toplevel flag in THD to check
whether SQL_LOG_BIN is ON in current session whatever the current is in sp or not.

set user variable max length on
fix_length_and_dec() stage
using real value length.

remove 'unsigned', 'zerofill' attributes
from DATA_TYPE column value.

            
The query cache module did not check for the SQL_NO_CACHE keyword before
attempting to query the hash lookup table. This had a small performance impact.

By introducing a check on the query string before obtaining the hash mutex
we can gain some performance if the SQL_NO_CACHE directive is used often.

Backporting patch to 5.0.

      
The problem here seem to be that when mysql
is redirecting stderr to a file, stderr becomes 
buffered, whereas it is unbuffered by definition.

The solution is to unbuffer it by setting buffer
to null.

of system errnos when opening a table are masked 
as ER_FILE_NOT_FOUND. This patch handles this as
"Operation failed" as well.

pushbuild".

Under new MTR the server is not restarted for every test, so
threads started in the previous test case can show up in the
results of SHOW PROCESSLIST statement in this test, causing a
test failure.

Since we are not really interested in results of SHOW PROCESSLIST
in this test but rather in fact that server doesn't crash when
executing this statement this fix simply disables output of this
statement.

This problem comes while inserting a duplicate row in merge table 
without key but the child table has a primary key. 
While forming the error message handler tries to locate the key field
which is creating this problem but as there is no key on the merge
table there is a segmentation fault.

Bug #42152: Race condition in lock_is_table_exclusive()

Detailed revision comments:

r4005 | marko | 2009-01-20 16:22:36 +0200 (Tue, 20 Jan 2009) | 8 lines
branches/5.1: lock_is_table_exclusive(): Acquire kernel_mutex before
accessing table->locks and release kernel_mutex before returning from
the function.  This fixes a portential race condition in the
"commit every 10,000 rows" in ALTER TABLE, CREATE INDEX, DROP INDEX,
and OPTIMIZE TABLE. (Bug #42152)

rb://80 approved by Heikki Tuuri

Bug #41571: MySQL segfaults after innodb recovery

Detailed revision comments:

r4004 | marko | 2009-01-20 16:19:00 +0200 (Tue, 20 Jan 2009) | 12 lines
branches/5.1: Merge r4003 from branches/5.0:

rec_set_nth_field(): When the field already is SQL null,
do nothing when it is being changed to SQL null. (Bug #41571)

Normally, MySQL does not pass "do-nothing" updates to the storage engine.
When it does and a column of an InnoDB table that is in ROW_FORMAT=COMPACT
is being updated from NULL to NULL, the InnoDB buffer pool will be corrupted
without this fix.

rb://81 approved by Heikki Tuuri

Bug #42075: dict_load_indexes failure in dict_load_table will corrupt the dictionary cache

Detailed revision comments:

r3930 | marko | 2009-01-14 15:51:30 +0200 (Wed, 14 Jan 2009) | 4 lines
branches/5.1: dict_load_table(): If dict_load_indexes() fails,
invoke dict_table_remove_from_cache() instead of dict_mem_table_free(),
so that the data dictionary will not point to freed data.
(Bug #42075, Issue #153, rb://76 approved by Heikki Tuuri)

Bug #38187: Error 153 when creating savepoints

Detailed revision comments:

r3911 | sunny | 2009-01-13 14:15:24 +0200 (Tue, 13 Jan 2009) | 13 lines
branches/5.1: Fix Bug#38187 Error 153 when creating savepoints
InnoDB previously treated savepoints as a stack e.g.,
  SAVEPOINT a;
  SAVEPOINT b;
  SAVEPOINT c;
  SAVEPOINT b; <- This would delete b and c.

This fix changes the behavior to:
  SAVEPOINT a;
  SAVEPOINT b;
  SAVEPOINT c;
  SAVEPOINT b; <- Does not delete savepoint c

Bug #41571: MySQL segfaults after innodb recovery

This 5.0 fix will not be pushed into 5.1; a separate fix (from
innodb-5.1-ss4007) will be pushed into 5.1+.

Detailed revision comments:

r4003 | marko | 2009-01-20 16:12:50 +0200 (Tue, 20 Jan 2009) | 10 lines
branches/5.0: rec_set_nth_field(): When the field already is SQL null,
do nothing when it is being changed to SQL null. (Bug #41571)

Normally, MySQL does not pass "do-nothing" updates to the storage engine.
When it does and a column of an InnoDB table that is in ROW_FORMAT=COMPACT
is being updated from NULL to NULL, the InnoDB buffer pool will be corrupted
without this fix.

rb://81 approved by Heikki Tuuri

Bug #18828: If InnoDB runs out of undo slots, it returns misleading 'table is full'

This is a backport of code already in 5.1+.  The error message change referred
to in the detailed revision comments is still pending.

Detailed revision comments:

r3937 | calvin | 2009-01-15 03:11:56 +0200 (Thu, 15 Jan 2009) | 17 lines
branches/5.0:

Backport the fix for Bug#18828. Return DB_TOO_MANY_CONCURRENT_TRXS
when we run out of UNDO slots in the rollback segment. The backport
is requested by MySQL under bug#41529 - Safe handling of InnoDB running
out of undo log slots.

This is a partial fix since the MySQL error code requested to properly
report the error condition back to the client has not yet materialized.
Currently we have #ifdef'd the error code translation in ha_innodb.cc.
This will have to be changed as and when MySQl add the new requested
code or an equivalent code that we can then use.

Given the above, currently we will get the old behavior, not the
"fixed" and intended behavior.

Approved by:	Heikki (on IM)

Bug #39939: DROP TABLE/DISCARD TABLESPACE takes long time in buf_LRU_invalidate_tablespace()

This was already fixed in 5.1+; this is a backport to 5.0.

Detailed revision comments:

r2743 | inaam | 2008-10-08 22:18:12 +0300 (Wed, 08 Oct 2008) | 13 lines
branches/5.0:

Backport of r2742 from branches/5.1:

Fix Bug#39939 DROP TABLE/DISCARD TABLESPACE takes long time in
buf_LRU_invalidate_tablespace()

Improve implementation of buf_LRU_invalidate_tablespace by attempting
hash index drop in batches instead of doing it one by one.

Reviewed by: Heikki, Sunny, Marko
Approved by: Heikki