diff options
| -rw-r--r-- | mysql-test/r/flush.result | 23 | ||||
| -rw-r--r-- | mysql-test/t/flush.test | 33 | ||||
| -rw-r--r-- | sql/mdl.h | 23 | ||||
| -rw-r--r-- | sql/sql_class.cc | 26 | ||||
| -rw-r--r-- | sql/sql_class.h | 14 | ||||
| -rw-r--r-- | sql/sql_parse.cc | 5 |
6 files changed, 109 insertions, 15 deletions
diff --git a/mysql-test/r/flush.result b/mysql-test/r/flush.result index bbfea2dade8..e36cd8a478f 100644 --- a/mysql-test/r/flush.result +++ b/mysql-test/r/flush.result @@ -466,3 +466,26 @@ ALTER TABLE t1 COMMENT 'test'; ERROR HY000: Table 't1' was locked with a READ lock and can't be updated UNLOCK TABLES; DROP TABLE t1; +# +# Test for bug #12641342 - "61401: UPDATE PERFORMANCE DEGRADES +# GRADUALLY IF A TRIGGER EXISTS". +# +# One of side-effects of this bug was that a transaction which +# involved DML statements requiring prelocking blocked concurrent +# FLUSH TABLES WITH READ LOCK for the whole its duration, while +# correct behavior in this case is to block FTWRL only for duration +# of individual DML statements. +DROP TABLE IF EXISTS t1; +CREATE TABLE t1 (id INT PRIMARY KEY, value INT); +INSERT INTO t1 VALUES (1, 1); +CREATE TRIGGER t1_au AFTER UPDATE ON t1 FOR EACH ROW SET @var = "a"; +BEGIN; +UPDATE t1 SET value= value + 1 WHERE id = 1; +# Switching to connection 'con1'. +# The below FLUSH TABLES WITH READ LOCK should succeed and +# should not be blocked by the transaction in default connection. +FLUSH TABLES WITH READ LOCK; +UNLOCK TABLES; +# Switching to connection 'default'. +COMMIT; +DROP TABLE t1; diff --git a/mysql-test/t/flush.test b/mysql-test/t/flush.test index 52ee6d2cf87..a4f1f19af27 100644 --- a/mysql-test/t/flush.test +++ b/mysql-test/t/flush.test @@ -668,3 +668,36 @@ ALTER TABLE t1 COMMENT 'test'; UNLOCK TABLES; DROP TABLE t1; + + +--echo # +--echo # Test for bug #12641342 - "61401: UPDATE PERFORMANCE DEGRADES +--echo # GRADUALLY IF A TRIGGER EXISTS". +--echo # +--echo # One of side-effects of this bug was that a transaction which +--echo # involved DML statements requiring prelocking blocked concurrent +--echo # FLUSH TABLES WITH READ LOCK for the whole its duration, while +--echo # correct behavior in this case is to block FTWRL only for duration +--echo # of individual DML statements. +--disable_warnings +DROP TABLE IF EXISTS t1; +--enable_warnings +CREATE TABLE t1 (id INT PRIMARY KEY, value INT); +INSERT INTO t1 VALUES (1, 1); +CREATE TRIGGER t1_au AFTER UPDATE ON t1 FOR EACH ROW SET @var = "a"; +BEGIN; +UPDATE t1 SET value= value + 1 WHERE id = 1; + +--echo # Switching to connection 'con1'. +connect(con1, localhost, root); +--echo # The below FLUSH TABLES WITH READ LOCK should succeed and +--echo # should not be blocked by the transaction in default connection. +FLUSH TABLES WITH READ LOCK; +UNLOCK TABLES; +disconnect con1; +--source include/wait_until_disconnected.inc + +--echo # Switching to connection 'default'. +connection default; +COMMIT; +DROP TABLE t1; diff --git a/sql/mdl.h b/sql/mdl.h index e0934cb732b..39e47da61dd 100644 --- a/sql/mdl.h +++ b/sql/mdl.h @@ -152,11 +152,24 @@ enum enum_mdl_type { /** Duration of metadata lock. */ -enum enum_mdl_duration { MDL_STATEMENT= 0, - MDL_TRANSACTION, - MDL_EXPLICIT, - /* This should be the last ! */ - MDL_DURATION_END }; +enum enum_mdl_duration { + /** + Locks with statement duration are automatically released at the end + of statement or transaction. + */ + MDL_STATEMENT= 0, + /** + Locks with transaction duration are automatically released at the end + of transaction. + */ + MDL_TRANSACTION, + /** + Locks with explicit duration survive the end of statement and transaction. + They have to be released explicitly by calling MDL_context::release_lock(). + */ + MDL_EXPLICIT, + /* This should be the last ! */ + MDL_DURATION_END }; /** Maximal length of key for metadata locking subsystem. */ diff --git a/sql/sql_class.cc b/sql/sql_class.cc index 7c2ed133f70..43575d135ee 100644 --- a/sql/sql_class.cc +++ b/sql/sql_class.cc @@ -3790,16 +3790,24 @@ void THD::set_mysys_var(struct st_my_thread_var *new_mysys_var) void THD::leave_locked_tables_mode() { + if (locked_tables_mode == LTM_LOCK_TABLES) + { + /* + When leaving LOCK TABLES mode we have to change the duration of most + of the metadata locks being held, except for HANDLER and GRL locks, + to transactional for them to be properly released at UNLOCK TABLES. + */ + mdl_context.set_transaction_duration_for_all_locks(); + /* + Make sure we don't release the global read lock and commit blocker + when leaving LTM. + */ + global_read_lock.set_explicit_lock_duration(this); + /* Also ensure that we don't release metadata locks for open HANDLERs. */ + if (handler_tables_hash.records) + mysql_ha_set_explicit_lock_duration(this); + } locked_tables_mode= LTM_NONE; - mdl_context.set_transaction_duration_for_all_locks(); - /* - Make sure we don't release the global read lock and commit blocker - when leaving LTM. - */ - global_read_lock.set_explicit_lock_duration(this); - /* Also ensure that we don't release metadata locks for open HANDLERs. */ - if (handler_tables_hash.records) - mysql_ha_set_explicit_lock_duration(this); } void THD::get_definer(LEX_USER *definer) diff --git a/sql/sql_class.h b/sql/sql_class.h index a2c622b2326..8a427057d83 100644 --- a/sql/sql_class.h +++ b/sql/sql_class.h @@ -2795,7 +2795,19 @@ public: { DBUG_ASSERT(locked_tables_mode == LTM_NONE); - mdl_context.set_explicit_duration_for_all_locks(); + if (mode_arg == LTM_LOCK_TABLES) + { + /* + When entering LOCK TABLES mode we should set explicit duration + for all metadata locks acquired so far in order to avoid releasing + them till UNLOCK TABLES statement. + We don't do this when entering prelocked mode since sub-statements + don't release metadata locks and restoring status-quo after leaving + prelocking mode gets complicated. + */ + mdl_context.set_explicit_duration_for_all_locks(); + } + locked_tables_mode= mode_arg; } void leave_locked_tables_mode(); diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc index 44a9243d8f5..36fdf376fa6 100644 --- a/sql/sql_parse.cc +++ b/sql/sql_parse.cc @@ -2027,6 +2027,11 @@ mysql_execute_command(THD *thd) */ if (stmt_causes_implicit_commit(thd, CF_IMPLICT_COMMIT_BEGIN)) { + /* + Note that this should never happen inside of stored functions + or triggers as all such statements prohibited there. + */ + DBUG_ASSERT(! thd->in_sub_stmt); /* Commit or rollback the statement transaction. */ thd->is_error() ? trans_rollback_stmt(thd) : trans_commit_stmt(thd); /* Commit the normal transaction if one is active. */ |