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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
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26
mysql-test/suite/innodb/r/alter_partitioned_debug.result
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@@ -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;