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MDEV-36227 Race condition between ALTER TABLE…EXCHANGE PARTITION and SELECT

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In commit 6e6a1b316c (MDEV-35000)
a race condition was exposed.

ha_innobase::check_if_incompatible_data(): If the statistics have
already been initialized for the table, skip the invocation of
innobase_copy_frm_flags_from_create_info() in order to avoid
unexpectedly ruining things for other threads that are concurrently
accessing the table.

dict_stats_save(): Add debug instrumentation that is necessary for
reproducing the interlocking of the failure scenario.
This commit is contained in:
Marko Mäkelä
2025-03-07 10:52:59 +02:00
parent 6e6a1b316c
commit 0331f1fff7
4 changed files with 77 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

26
mysql-test/suite/innodb/r/alter_partitioned_debug.result
View File

@@ -1,4 +1,5 @@
CREATE TABLE t1 (a INT, b VARCHAR(10)) ENGINE=InnoDB
STATS_PERSISTENT=1 STATS_AUTO_RECALC=0
PARTITION BY RANGE(a)
(PARTITION pa VALUES LESS THAN (3),
PARTITION pb VALUES LESS THAN (5));
@@ -19,9 +20,30 @@ connection ddl;
ERROR 23000: Duplicate entry '2-two' for key 'a'
connection default;
DELETE FROM t1;
disconnect ddl;
SET DEBUG_SYNC = 'RESET';
CHECK TABLE t1;
Table Op Msg_type Msg_text
test.t1 check status OK
DROP TABLE t1;
CREATE TABLE t(a INT, b VARCHAR(10)) ENGINE=InnoDB
STATS_PERSISTENT=1 STATS_AUTO_RECALC=1;
RENAME TABLE t TO u;
DELETE FROM mysql.innodb_table_stats WHERE table_name='u';
DELETE FROM mysql.innodb_index_stats WHERE table_name='u';
SET STATEMENT debug_dbug='+d,dict_stats_save_exit_notify_and_wait' FOR
SELECT * FROM u;
connection ddl;
SET DEBUG_SYNC='open_tables_after_open_and_process_table
WAIT_FOR dict_stats_save_finished';
ALTER TABLE t1 EXCHANGE PARTITION pb WITH TABLE u;
connect sync,localhost,root;
SET DEBUG_SYNC='now SIGNAL dict_stats_save_unblock';
disconnect sync;
connection default;
a b
connection ddl;
disconnect ddl;
connection default;
SELECT * FROM u;
a b
SET DEBUG_SYNC = 'RESET';
DROP TABLE t1,u;

42
mysql-test/suite/innodb/t/alter_partitioned_debug.test
View File

@@ -4,6 +4,7 @@
--source include/have_debug_sync.inc
CREATE TABLE t1 (a INT, b VARCHAR(10)) ENGINE=InnoDB
STATS_PERSISTENT=1 STATS_AUTO_RECALC=0
PARTITION BY RANGE(a)
(PARTITION pa VALUES LESS THAN (3),
PARTITION pb VALUES LESS THAN (5));
@@ -26,9 +27,46 @@ reap;
connection default;
DELETE FROM t1;
disconnect ddl;
SET DEBUG_SYNC = 'RESET';
CHECK TABLE t1;
DROP TABLE t1;
CREATE TABLE t(a INT, b VARCHAR(10)) ENGINE=InnoDB
STATS_PERSISTENT=1 STATS_AUTO_RECALC=1;
RENAME TABLE t TO u;
DELETE FROM mysql.innodb_table_stats WHERE table_name='u';
DELETE FROM mysql.innodb_index_stats WHERE table_name='u';
send SET STATEMENT debug_dbug='+d,dict_stats_save_exit_notify_and_wait' FOR
SELECT * FROM u;
connection ddl;
SET DEBUG_SYNC='open_tables_after_open_and_process_table
WAIT_FOR dict_stats_save_finished';
send ALTER TABLE t1 EXCHANGE PARTITION pb WITH TABLE u;
connect sync,localhost,root;
let $wait_condition=
select count(*) = 1 from information_schema.processlist
where state = 'debug sync point: now'
and info like 'SET STATEMENT debug_dbug%SELECT * FROM u';
--source include/wait_condition.inc
let $wait_condition=
select count(*) = 1 from information_schema.processlist
where state = 'Waiting for table metadata lock'
and info like 'ALTER TABLE t1 EXCHANGE PARTITION pb WITH TABLE u';
--source include/wait_condition.inc
SET DEBUG_SYNC='now SIGNAL dict_stats_save_unblock';
disconnect sync;
connection default;
reap;
connection ddl;
reap;
disconnect ddl;
connection default;
SELECT * FROM u;
SET DEBUG_SYNC = 'RESET';
DROP TABLE t1,u;

7
storage/innobase/dict/dict0stats.cc
View File

@@ -2887,6 +2887,13 @@ dberr_t dict_stats_save(dict_table_t* table, index_id_t index_id)
STRING_WITH_LEN("now SIGNAL dict_stats_save_finished"));
});
);
DBUG_EXECUTE_IF("dict_stats_save_exit_notify_and_wait",
SCOPE_EXIT([] {
debug_sync_set_action(current_thd,
STRING_WITH_LEN("now SIGNAL dict_stats_save_finished"
" WAIT_FOR dict_stats_save_unblock"));
});
);
#endif /* ENABLED_DEBUG_SYNC */
if (high_level_read_only) {

7
storage/innobase/handler/ha_innodb.cc
View File

@@ -17424,7 +17424,12 @@ ha_innobase::check_if_incompatible_data(
param_new = info->option_struct;
param_old = table->s->option_struct;
innobase_copy_frm_flags_from_create_info(m_prebuilt->table, info);
m_prebuilt->table->stats_mutex_lock();
if (!m_prebuilt->table->stat_initialized()) {
innobase_copy_frm_flags_from_create_info(
m_prebuilt->table, info);
}
m_prebuilt->table->stats_mutex_unlock();
if (table_changes != IS_EQUAL_YES) {