Problem described in this bug report affects MyISAM tables only.
Running mysqld --flush instructs mysqld to sync all changes to disk
after each SQL statement. It worked well for INSERT and DELETE
statements, but it did sync for UPDATE only in case if there was
index change (change of colum that has an index). If no updated column
has an index, data wasn't synced to disk.
This fix makes UPDATE statement to sync data to disk even if there is
no index change (that is only data change) and mysqld is run with
--flush option.
(this is not a fix to the bug, but simply to disable the test in
order to push a 5.0 to 5.1 merge)
This merge contains:
Push by holyfoot@production.mysql.com on Tue Jul 25 13:41:40 2006:
bk clone -l -r'holyfoot/hf@mysql.com/deer.(none)|ChangeSet|20060725085017|41021' mysql-5.0 tmp_merge
into govinda.patg.net:/home/patg/mysql-build/mysql-5.1-5.0-merge2
Push by holyfoot@production.mysql.com on Tue Jul 25 13:41:40 2006:
bk clone -l -r'holyfoot/hf@mysql.com/deer.(none)|ChangeSet|20060725085017|41021' mysql-5.0 tmp_merge
we didn't check for NULL value of the
lex_create_info->db_type pointer.
The pointer is NULL in the case, when the engine name is
unknown to the server. This happens with NDB on Windows.
The following procedure was not possible if max_sp_recursion_depth is 0
create procedure show_proc() show create procedure show_proc;
Actually there is no recursive call but the limit is checked.
Solved by temporarily increasing the thread's limit just before the fetch from cache
and decreasing after that.
gets deadlocked when dropping w/ log on"
Log tables rely on concurrent insert machinery to add data.
This means that log tables are always opened and locked by
special (artificial) logger threads. Because of this, the thread
which tries to drop a log table starts to wait for the table
to be unlocked. Which will happen only if the log table is disabled.
Alike situation happens if one tries to alter a log table.
However in addition to the problem above, alter table calls
check_if_locking_is_allowed() routine for the engine. The
routine does not allow alter for the log tables. So, alter
doesn't start waiting forever for logs to be disabled, but
returns with an error.
Another problem is that not all engines could be used for
the log tables. That's because they need concurrent insert.
In this patch we:
(1) Explicitly disallow to drop/alter a log table if it
is currently used by the logger.
(2) Update MyISAM to support log tables
(3) Allow to drop log tables/alter log tables if log is
disabled
At the same time we (4) Disallow to alter log tables to
unsupported engine (after this patch CSV and MyISAM are
alowed)
Recommit with review fixes.
Due to incorrect handling of FLUSH TABLES, log tables were marked for flush,
but not reopened. Later we started to wait for the log table to be closed
(disabled) after the flush. And as nobody disabled logs in concurrent treads,
the command lasted forever.
After internal consultations it was decided to skip logs during FLUSH TABLES.
The reasoning is that logging is done in the "log device", whatever it is
which is always active and controlled by FLUSH LOGS. So, to flush logs
one should use FLUSH LOGS, and not FLUSH TABLES.
privileges
This problem is 4.1 specific. It doesn't affect 4.0 and was fixed
in 5.x before.
Having any mysql user who is allowed to issue multi table update
statement and any column/table grants, allows this user to update
any table on a server (mysql grant tables are not exception).
check_grant() accepts number of tables (in table list) to be checked
in 5-th param. While checking grants for multi table update, number
of tables must be 1. It must never be 0 (actually we have
DBUG_ASSERT(number > 0) in 5.x in grant_check() function).
