database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2026-01-06 05:22:24 +03:00
Code Activity

Backport of revno: 2617.71.1

Browse Source 
Bug#42546 Backup: RESTORE fails, thinking it finds an existing table

The problem occured when a MDL locking conflict happened for a non-existent 
table between a CREATE and a INSERT statement. The code for CREATE 
interpreted this lock conflict to mean that the table existed, 
which meant that the statement failed when it should not have.
The problem could occur for CREATE TABLE, CREATE TABLE LIKE and
ALTER TABLE RENAME.

This patch fixes the problem for CREATE TABLE and CREATE TABLE LIKE.
It is based on code backported from the mysql-6.1-fk tree written
by Dmitry Lenev. CREATE now uses normal open_and_lock_tables() code 
to acquire exclusive locks. This means that for the test case in the bug 
description, CREATE will wait until INSERT completes so that it can 
get the exclusive lock. This resolves the reported bug.

The patch also prohibits CREATE TABLE and CREATE TABLE LIKE under 
LOCK TABLES. Note that this is an incompatible change and must 
be reflected in the documentation. Affected test cases have been
updated.

mdl_sync.test contains tests for CREATE TABLE and CREATE TABLE LIKE.

Fixing the issue for ALTER TABLE RENAME is beyond the scope of this
patch. ALTER TABLE cannot be prohibited from working under LOCK TABLES
as this could seriously impact customers and a proper fix would require
a significant rewrite.
This commit is contained in:
Jon Olav Hauglid
2009-12-10 11:53:20 +01:00
parent f3bc2406b0
commit 5e1dfa4c06
21 changed files with 465 additions and 415 deletions
Download Patch File Download Diff File Expand all files Collapse all files

79
sql/sql_parse.cc
View File

@@ -2245,9 +2245,9 @@ case SQLCOM_PREPARE:
{
DBUG_ASSERT(first_table == all_tables && first_table != 0);
bool link_to_local;
// Skip first table, which is the table we are creating
TABLE_LIST *create_table= lex->unlink_first_table(&link_to_local);
TABLE_LIST *select_tables= lex->query_tables;
TABLE_LIST *create_table= first_table;
TABLE_LIST *select_tables= lex->create_last_non_select_table->next_global;
/*
Code below (especially in mysql_create_table() and select_create
methods) may modify HA_CREATE_INFO structure in LEX, so we have to
@@ -2327,6 +2327,10 @@ case SQLCOM_PREPARE:
}
#endif
/* Set strategies: reset default or 'prepared' values. */
create_table->open_strategy= TABLE_LIST::OPEN_IF_EXISTS;
create_table->lock_strategy= TABLE_LIST::EXCLUSIVE_DOWNGRADABLE_MDL;
/*
Close any open handlers for the table
*/
@@ -2389,15 +2393,8 @@ case SQLCOM_PREPARE:
goto end_with_restore_list;
}
if (!(create_info.options & HA_LEX_CREATE_TMP_TABLE))
{
lex->link_first_table_back(create_table, link_to_local);
/* Set strategies: reset default or 'prepared' values. */
create_table->open_strategy= TABLE_LIST::OPEN_IF_EXISTS;
create_table->lock_strategy= TABLE_LIST::EXCLUSIVE_DOWNGRADABLE_MDL;
}
if (!(res= open_and_lock_tables(thd, lex->query_tables)))
if (!(res= open_and_lock_tables_derived(thd, lex->query_tables, TRUE,
MYSQL_OPEN_TAKE_UPGRADABLE_MDL)))
{
/*
Is table which we are changing used somewhere in other parts
@@ -2406,7 +2403,6 @@ case SQLCOM_PREPARE:
if (!(create_info.options & HA_LEX_CREATE_TMP_TABLE))
{
TABLE_LIST *duplicate;
create_table= lex->unlink_first_table(&link_to_local);
if ((duplicate= unique_table(thd, create_table, select_tables, 0)))
{
update_non_unique_table_error(create_table, "CREATE", duplicate);
@@ -2432,6 +2428,13 @@ case SQLCOM_PREPARE:
}
}
/*
Remove target table from main select and name resolution
context. This can't be done earlier as it will break view merging in
statements like "CREATE TABLE IF NOT EXISTS existing_view SELECT".
*/
lex->unlink_first_table(&link_to_local);
/*
select_create is currently not re-execution friendly and
needs to be created for every execution of a PS/SP.
@@ -2451,33 +2454,32 @@ case SQLCOM_PREPARE:
res= handle_select(thd, lex, result, 0);
delete result;
}
lex->link_first_table_back(create_table, link_to_local);
}
else if (!(create_info.options & HA_LEX_CREATE_TMP_TABLE))
create_table= lex->unlink_first_table(&link_to_local);
}
else
{
/* So that CREATE TEMPORARY TABLE gets to binlog at commit/rollback */
if (create_info.options & HA_LEX_CREATE_TMP_TABLE)
thd->options|= OPTION_KEEP_LOG;
/* regular create */
if (create_info.options & HA_LEX_CREATE_TABLE_LIKE)
{
/* CREATE TABLE ... LIKE ... */
res= mysql_create_like_table(thd, create_table, select_tables,
&create_info);
}
else
{
res= mysql_create_table(thd, create_table->db,
create_table->table_name, &create_info,
&alter_info, 0, 0);
/* Regular CREATE TABLE */
res= mysql_create_table(thd, create_table,
&create_info, &alter_info);
}
if (!res)
my_ok(thd);
my_ok(thd);
}
/* put tables back for PS rexecuting */
end_with_restore_list:
lex->link_first_table_back(create_table, link_to_local);
break;
}
case SQLCOM_CREATE_INDEX:
@@ -2705,7 +2707,8 @@ end_with_restore_list:
}
/* Ignore temporary tables if this is "SHOW CREATE VIEW" */
first_table->skip_temporary= 1;
first_table->open_type= OT_BASE_ONLY;
}
else
{
@@ -7194,6 +7197,34 @@ bool insert_precheck(THD *thd, TABLE_LIST *tables)
}
/**
Set proper open mode and table type for element representing target table
of CREATE TABLE statement, also adjust statement table list if necessary.
*/
void create_table_set_open_action_and_adjust_tables(LEX *lex)
{
TABLE_LIST *create_table= lex->query_tables;
if (lex->create_info.options & HA_LEX_CREATE_TMP_TABLE)
create_table->open_type= OT_TEMPORARY_ONLY;
else if (!lex->select_lex.item_list.elements)
create_table->open_type= OT_BASE_ONLY;
if (!lex->select_lex.item_list.elements)
{
/*
Avoid opening and locking target table for ordinary CREATE TABLE
or CREATE TABLE LIKE for write (unlike in CREATE ... SELECT we
won't do any insertions in it anyway). Not doing this causes
problems when running CREATE TABLE IF NOT EXISTS for already
existing log table.
*/
create_table->lock_type= TL_READ;
}
}
/**
CREATE TABLE query pre-check.