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Fixed bug mdev-3891.

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If a query referenced some system statistical tables, but not all of them,
then executing an ANALYZE command simultaneously with this query could
lead to a deadlock.
The fix prohibited reading statistics from system statistical tables
for such queries.

Removed the function unlock_tables_n_open_system_tables_for_write()
as not used anymore.
Performed some minor refactoring of the code in sql_statistics.cc.
This commit is contained in:
Igor Babaev
2012-12-12 23:16:54 -08:00
parent 109c104d07
commit 65820439bd
6 changed files with 140 additions and 107 deletions
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70
sql/sql_base.cc
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@@ -9604,6 +9604,12 @@ has_write_table_auto_increment_not_first_in_pk(TABLE_LIST *tables)
must call close_system_tables() to close systems tables opened
with this call.
NOTES
In some situations we use this function to open system tables for
writing. It happens, for examples, with statistical tables when
they are updated by an ANALYZE command. In these cases we should
guarantee that system tables will not be deadlocked.
RETURN
FALSE Success
TRUE Error
@@ -9648,70 +9654,6 @@ open_system_tables_for_read(THD *thd, TABLE_LIST *table_list,
}
/*
Unlock opened tables and open and lock system tables for write.
SYNOPSIS
unlock_tables_n_open_system_tables_for_write()
thd Thread context.
table_list List of tables to open.
backup Pointer to Open_tables_state instance where
information about currently open tables will be
saved, and from which will be restored when we will
end work with system tables.
DESCRIPTION
The function first unlocks the opened tables, but do not close them.
Then it opens and locks for write the specified system tables.
NOTE
The system tables cannot be locked for write without unlocking
the current opened tables. Yet in some cases we still need valid TABLE
structures for these tables to be able to extract data that is to be
written into the system tables.
This function is used when updating the statistical tables.
RETURN
FALSE Success
TRUE Error
*/
bool
unlock_tables_n_open_system_tables_for_write(THD *thd,
TABLE_LIST *table_list,
Open_tables_backup *backup)
{
Query_tables_list query_tables_list_backup;
LEX *lex= thd->lex;
DBUG_ENTER("unlock_tables_n_open_system_tables_for_write");
lex->reset_n_backup_query_tables_list(&query_tables_list_backup);
thd->reset_n_backup_open_tables_state(backup);
if (open_and_lock_tables(thd, table_list, FALSE,
MYSQL_OPEN_IGNORE_FLUSH | MYSQL_LOCK_IGNORE_TIMEOUT))
{
lex->restore_backup_query_tables_list(&query_tables_list_backup);
goto error;
}
for (TABLE_LIST *tables= table_list; tables; tables= tables->next_global)
{
DBUG_ASSERT(tables->table->s->table_category == TABLE_CATEGORY_SYSTEM);
tables->table->use_all_columns();
}
lex->restore_backup_query_tables_list(&query_tables_list_backup);
DBUG_RETURN(FALSE);
error:
close_system_tables(thd, backup);
DBUG_RETURN(TRUE);
}
/*
Close system tables, opened with open_system_tables_for_read().