* Ingo Struewing <Ingo.Struewing@stripped> [09/06/19 19:12]:
> #At file:///home2/mydev/bzrroot/mysql-6.0-bug20667-1/ based on
> revid:charles.bell@stripped
>
> 2825 Ingo Struewing 2009-06-19
> Bug#20667 - Truncate table fails for a write locked table
>
> TRUNCATE TABLE was not allowed under LOCK TABLES.
>
> The patch removes this restriction. mysql_truncate()
> does now handle that case.
The patch is, generally, OK.
However, instead of get_table() method that you implemented,
I think one should use an already existing function
find_write_locked_table(), which is used in, e.g. DROP TABLE
under LOCK TABLES.
Note that we can't simply use open_and_lock_single_table(),
since we want to be able to truncate damaged tables.
I wrote a comment about that. Please see the patch at the end of
the reply. Note that my patch is a sketch, please feel free to
improve on it.
Some more comments inline.
> @ mysql-test/r/merge.result
> Bug#20667 - Truncate table fails for a write locked table
> Updated test result.
<cut>
> === modified file 'mysql-test/t/merge.test'
> --- a/mysql-test/t/merge.test 2009-04-22 10:02:28 +0000
> +++ b/mysql-test/t/merge.test 2009-06-19 14:45:15 +0000
> @@ -688,12 +688,16 @@ SELECT * FROM t3;
> --echo # Truncate MERGE table under locked tables.
> LOCK TABLE t1 WRITE, t2 WRITE, t3 WRITE;
> INSERT INTO t1 VALUES (1);
> ---error ER_LOCK_OR_ACTIVE_TRANSACTION
> TRUNCATE TABLE t3;
> SELECT * FROM t3;
> +UNLOCK TABLES;
> +SELECT * FROM t1;
> +SELECT * FROM t2;
> --echo #
> --echo # Truncate child table under locked tables.
> ---error ER_LOCK_OR_ACTIVE_TRANSACTION
> +LOCK TABLE t1 WRITE, t2 WRITE, t3 WRITE;
> +INSERT INTO t1 VALUES (1);
> +INSERT INTO t2 VALUES (2);
> TRUNCATE TABLE t1;
> SELECT * FROM t3;
> UNLOCK TABLES;
> @@ -719,14 +723,18 @@ SELECT * FROM t3;
> INSERT INTO t1 VALUES (1);
> CREATE TABLE t4 (c1 INT, INDEX(c1));
> LOCK TABLE t4 WRITE;
> ---error ER_LOCK_OR_ACTIVE_TRANSACTION
> TRUNCATE TABLE t3;
> SELECT * FROM t3;
> +SELECT * FROM t1;
> +SELECT * FROM t2;
> --echo #
> --echo # Truncate temporary child table under locked tables.
> ---error ER_LOCK_OR_ACTIVE_TRANSACTION
> +INSERT INTO t1 VALUES (1);
> +INSERT INTO t2 VALUES (2);
> TRUNCATE TABLE t1;
> SELECT * FROM t3;
> +SELECT * FROM t1;
> +SELECT * FROM t2;
> UNLOCK TABLES;
> DROP TABLE t1, t2, t3, t4;
Good.
> === modified file 'mysql-test/t/truncate.test'
> --- a/mysql-test/t/truncate.test 2007-04-17 10:32:01 +0000
> +++ b/mysql-test/t/truncate.test 2009-06-19 14:45:15 +0000
> @@ -69,3 +69,29 @@ drop table t1;
>
> # End of 5.0 tests
>
> +--echo #
> +--echo # Bug#20667 - Truncate table fails for a write locked table
> +--echo #
> +CREATE TABLE t1 (c1 INT) ENGINE=MyISAM;
> +LOCK TABLE t1 WRITE;
> +INSERT INTO t1 VALUES (1);
> +SELECT * FROM t1;
> +TRUNCATE TABLE t1;
> +SELECT * FROM t1;
> +UNLOCK TABLES;
> +#
> +LOCK TABLE t1 READ;
> +--error ER_TABLE_NOT_LOCKED_FOR_WRITE
> +TRUNCATE TABLE t1;
> +UNLOCK TABLES;
> +#
> +CREATE TABLE t2 (c1 INT) ENGINE=MyISAM;
> +LOCK TABLE t2 WRITE;
> +--error ER_TABLE_NOT_LOCKED
> +TRUNCATE TABLE t1;
> +UNLOCK TABLES;
> +DROP TABLE t1;
> +DROP TABLE t2;
> +
> +--echo # End of 6.0 tests
> +
Good.
> === modified file 'sql/sql_delete.cc'
> --- a/sql/sql_delete.cc 2009-05-31 12:05:01 +0000
> +++ b/sql/sql_delete.cc 2009-06-19 14:45:15 +0000
Please use the attached patch as a basis.
> === modified file 'sql/sql_parse.cc'
> --- a/sql/sql_parse.cc 2009-06-12 02:01:08 +0000
> +++ b/sql/sql_parse.cc 2009-06-19 14:45:15 +0000
> @@ -3376,7 +3376,7 @@ end_with_restore_list:
> Don't allow this within a transaction because we want to use
> re-generate table
> */
> - if (thd->locked_tables_mode || thd->active_transaction())
> + if (thd->active_transaction())
> {
> my_message(ER_LOCK_OR_ACTIVE_TRANSACTION,
> ER(ER_LOCK_OR_ACTIVE_TRANSACTION), MYF(0));
Correct.
Please add a test case for truncate table v1, where v1 is a view
(under LOCK TABLES).
Please see the diff below.
Thank you so much for looking at this!
=== modified file 'sql/sql_delete.cc'
--- sql/sql_delete.cc 2009-06-19 09:28:44 +0000
+++ sql/sql_delete.cc 2009-07-16 19:27:12 +0000
@@ -1129,6 +1129,12 @@ bool mysql_truncate(THD *thd, TABLE_LIST
if (!dont_send_ok)
{
enum legacy_db_type table_type;
+ /*
+ FIXME: Code of TRUNCATE breaks the meta-data
+ locking protocol since it tries to find out the table storage
+ engine and therefore accesses table in some way without holding
+ any kind of meta-data lock.
+ */
mysql_frm_type(thd, path, &table_type);
if (table_type == DB_TYPE_UNKNOWN)
{
@@ -1143,24 +1149,46 @@ bool mysql_truncate(THD *thd, TABLE_LIST
if (table_type == DB_TYPE_NDBCLUSTER)
global_schema_lock_guard.lock();
- /*
- FIXME: Actually code of TRUNCATE breaks meta-data locking protocol since
- tries to get table enging and therefore accesses table in some way
- without holding any kind of meta-data lock.
- */
- mdl_request= MDL_request::create(0, table_list->db,
- table_list->table_name, thd->mem_root);
- mdl_request->set_type(MDL_EXCLUSIVE);
- thd->mdl_context.add_request(mdl_request);
- if (thd->mdl_context.acquire_exclusive_locks())
+
+ mysql_ha_rm_tables(thd, table_list);
+
+ if (thd->locked_tables_mode)
{
- thd->mdl_context.remove_request(mdl_request);
- DBUG_RETURN(TRUE);
+ if (!(table= find_write_locked_table(thd->open_tables, table_list->db,
+ table_list->table_name)))
+ DBUG_RETURN(TRUE);
+ if (wait_while_table_is_used(thd, table, HA_EXTRA_FORCE_REOPEN))
+ goto end;
+ close_all_tables_for_name(thd, table->s, FALSE);
+ }
+ else
+ {
+ /*
+ Even though we could use the previous execution branch
+ here just as well, we must not try to open the table:
+ MySQL manual documents that TRUNCATE can be used to
+ repair a damaged table, i.e. a table that can not be
+ fully "opened". In particular MySQL manual says:
+
+ As long as the table format file tbl_name.frm is valid,
+ the table can be re-created as an empty table with TRUNCATE
+ TABLE, even if the data or index files have become corrupted.
+ */
+
+ mdl_request= MDL_request::create(0, table_list->db,
+ table_list->table_name, thd->mem_root);
+ mdl_request->set_type(MDL_EXCLUSIVE);
+ thd->mdl_context.add_request(mdl_request);
+ if (thd->mdl_context.acquire_exclusive_locks())
+ {
+ thd->mdl_context.remove_request(mdl_request);
+ DBUG_RETURN(TRUE);
+ }
+ pthread_mutex_lock(&LOCK_open);
+ tdc_remove_table(thd, TDC_RT_REMOVE_ALL, table_list->db,
+ table_list->table_name);
+ pthread_mutex_unlock(&LOCK_open);
}
- pthread_mutex_lock(&LOCK_open);
- tdc_remove_table(thd, TDC_RT_REMOVE_ALL, table_list->db,
- table_list->table_name);
- pthread_mutex_unlock(&LOCK_open);
}
/*
@@ -1178,6 +1206,12 @@ bool mysql_truncate(THD *thd, TABLE_LIST
end:
if (!dont_send_ok)
{
+ if (thd->locked_tables_mode &&
thd->locked_tables_list.reopen_tables(thd))
+ thd->locked_tables_list.unlink_all_closed_tables();
+ /*
+ Even if we failed to reopen some tables,
+ the operation itself succeeded, write the binlog.
+ */
if (!error)
{
/*
@@ -1193,14 +1227,6 @@ end:
thd->mdl_context.remove_request(mdl_request);
}
}
- else if (error)
- {
- if (mdl_request)
- {
- thd->mdl_context.release_lock(mdl_request->ticket);
- thd->mdl_context.remove_request(mdl_request);
- }
- }
DBUG_RETURN(error);
trunc_by_del:
=== modified file 'sql/sql_parse.cc'
--- sql/sql_parse.cc 2009-07-10 12:31:32 +0000
+++ sql/sql_parse.cc 2009-07-16 17:13:55 +0000
@@ -3316,7 +3316,7 @@ end_with_restore_list:
Don't allow this within a transaction because we want to use
re-generate table
*/
- if (thd->locked_tables_mode || thd->active_transaction())
+ if (thd->active_transaction())
{
my_message(ER_LOCK_OR_ACTIVE_TRANSACTION,
ER(ER_LOCK_OR_ACTIVE_TRANSACTION), MYF(0));
--
kostja
