# # Test how we handle locking in various cases when # we read data from MyISAM tables. # # In this test we mostly check that the SQL-layer correctly # determines the type of thr_lock.c lock for a table being # read. # I.e. that it disallows concurrent inserts when the statement # is going to be written to the binary log and therefore # should be serialized, and allows concurrent inserts when # such serialization is not necessary (e.g. when # the statement is not written to binary log). # # Force concurrent inserts to be performed even if the table # has gaps. This allows to simplify clean up in scripts # used below (instead of backing up table being inserted # into and then restoring it from backup at the end of the # script we can simply delete rows which were inserted). set @old_concurrent_insert= @@global.concurrent_insert; set @@global.concurrent_insert= 2; select @@global.concurrent_insert; @@global.concurrent_insert ALWAYS # Prepare playground by creating tables, views, # routines and triggers used in tests. connect con1, localhost, root,,; connect con2, localhost, root,,; connection default; drop table if exists t0, t1, t2, t3, t4, t5; drop view if exists v1, v2; drop procedure if exists p1; drop procedure if exists p2; drop procedure if exists p3; drop function if exists f1; drop function if exists f2; drop function if exists f3; drop function if exists f4; drop function if exists f5; drop function if exists f6; drop function if exists f7; drop function if exists f8; drop function if exists f9; drop function if exists f10; drop function if exists f11; drop function if exists f12; drop function if exists f13; drop function if exists f14; drop function if exists f15; drop function if exists f16; drop function if exists f17; create table t1 (i int primary key); insert into t1 values (1), (2), (3), (4), (5); create table t2 (j int primary key); insert into t2 values (1), (2), (3), (4), (5); create table t3 (k int primary key); insert into t3 values (1), (2), (3); create table t4 (l int primary key); insert into t4 values (1); create table t5 (l int primary key); insert into t5 values (1); create view v1 as select i from t1; create view v2 as select j from t2 where j in (select i from t1); create procedure p1(k int) insert into t2 values (k); create function f1() returns int begin declare j int; select i from t1 where i = 1 into j; return j; end| Warnings: Warning 1287 ' INTO FROM...' instead create function f2() returns int begin declare k int; select i from t1 where i = 1 into k; insert into t2 values (k + 5); return 0; end| Warnings: Warning 1287 ' INTO FROM...' instead create function f3() returns int begin return (select i from t1 where i = 3); end| create function f4() returns int begin if (select i from t1 where i = 3) then return 1; else return 0; end if; end| create function f5() returns int begin insert into t2 values ((select i from t1 where i = 1) + 5); return 0; end| create function f6() returns int begin declare k int; select i from v1 where i = 1 into k; return k; end| Warnings: Warning 1287 ' INTO FROM...' instead create function f7() returns int begin declare k int; select j from v2 where j = 1 into k; return k; end| Warnings: Warning 1287 ' INTO FROM...' instead create function f8() returns int begin declare k int; select i from v1 where i = 1 into k; insert into t2 values (k+5); return k; end| Warnings: Warning 1287 ' INTO FROM...' instead create function f9() returns int begin update v2 set j=j+10 where j=1; return 1; end| create function f10() returns int begin return f1(); end| create function f11() returns int begin declare k int; set k= f1(); insert into t2 values (k+5); return k; end| create function f12(p int) returns int begin insert into t2 values (p); return p; end| create function f13(p int) returns int begin return p; end| create procedure p2(inout p int) begin select i from t1 where i = 1 into p; end| Warnings: Warning 1287 ' INTO FROM...' instead create function f14() returns int begin declare k int; call p2(k); insert into t2 values (k+5); return k; end| create function f15() returns int begin declare k int; call p2(k); return k; end| create function f16() returns int begin create temporary table if not exists temp1 (a int); insert into temp1 select * from t1; drop temporary table temp1; return 1; end| create function f17() returns int begin declare j int; select i from t1 where i = 1 into j; call p3; return 1; end| Warnings: Warning 1287 ' INTO FROM...' instead create procedure p3() begin create temporary table if not exists temp1 (a int); insert into temp1 select * from t1; drop temporary table temp1; end| create trigger t4_bi before insert on t4 for each row begin declare k int; select i from t1 where i=1 into k; set new.l= k+1; end| Warnings: Warning 1287 ' INTO FROM...' instead create trigger t4_bu before update on t4 for each row begin if (select i from t1 where i=1) then set new.l= 2; end if; end| create trigger t4_bd before delete on t4 for each row begin if !(select i from v1 where i=1) then signal sqlstate '45000'; end if; end| create trigger t5_bi before insert on t5 for each row begin set new.l= f1()+1; end| create trigger t5_bu before update on t5 for each row begin declare j int; call p2(j); set new.l= j + 1; end| # # Set common variables to be used by the scripts # called below. # connection con1; set @save_dbug=@@debug_dbug; set debug_dbug="+d,cache_sp_in_show_create"; # Cache all functions used in the tests below so statements # calling them won't need to open and lock mysql.proc table # and we can assume that each statement locks its tables # once during its execution. show create procedure p1; show create procedure p2; show create procedure p3; show create function f1; show create function f2; show create function f3; show create function f4; show create function f5; show create function f6; show create function f7; show create function f8; show create function f9; show create function f10; show create function f11; show create function f12; show create function f13; show create function f14; show create function f15; show create function f16; show create function f17; set debug_dbug=@save_dbug; connection default; # # 1. Statements that read tables and do not use subqueries. # # # 1.1 Simple SELECT statement. # # No locks are necessary as this statement won't be written # to the binary log and thanks to how MyISAM works SELECT # will see version of the table prior to concurrent insert. connection default; Success: 'select * from t1' allows concurrent inserts into 't1'. # # 1.2 Multi-UPDATE statement. # # Has to take shared locks on rows in the table being read as this # statement will be written to the binary log and therefore should # be serialized with concurrent statements. connection default; Success: 'update t2, t1 set j= j - 1 where i = j' doesn't allow concurrent inserts into 't1'. # # 1.3 Multi-DELETE statement. # # The above is true for this statement as well. connection default; Success: 'delete t2 from t1, t2 where i = j' doesn't allow concurrent inserts into 't1'. # # 1.4 DESCRIBE statement. # # This statement does not really read data from the # target table and thus does not take any lock on it. # We check this for completeness of coverage. lock table t1 write; connection con1; # This statement should not be blocked. describe t1; connection default; unlock tables; # # 1.5 SHOW statements. # # The above is true for SHOW statements as well. lock table t1 write; connection con1; # These statements should not be blocked. show keys from t1; connection default; unlock tables; # # 2. Statements which read tables through subqueries. # # # 2.1 CALL with a subquery. # # A strong lock is not necessary as this statement is not # written to the binary log as a whole (it is written # statement-by-statement). connection default; Success: 'call p1((select i + 5 from t1 where i = 1))' allows concurrent inserts into 't1'. # # 2.2 CREATE TABLE with a subquery. # # Has to take a strong lock on the table being read as # this statement is written to the binary log and therefore # should be serialized with concurrent statements. connection default; Success: 'create table t0 select * from t1' doesn't allow concurrent inserts into 't1'. drop table t0; connection default; Success: 'create table t0 select j from t2 where j in (select i from t1)' doesn't allow concurrent inserts into 't1'. drop table t0; # # 2.3 DELETE with a subquery. # # The above is true for this statement as well. connection default; Success: 'delete from t2 where j in (select i from t1)' doesn't allow concurrent inserts into 't1'. # # 2.4 MULTI-DELETE with a subquery. # # Same is true for this statement as well. connection default; Success: 'delete t2 from t3, t2 where k = j and j in (select i from t1)' doesn't allow concurrent inserts into 't1'. # # 2.5 DO with a subquery. # # A strong lock is not necessary as it is not logged. connection default; Success: 'do (select i from t1 where i = 1)' allows concurrent inserts into 't1'. # # 2.6 INSERT with a subquery. # # Has to take a strong lock on the table being read as # this statement is written to the binary log and therefore # should be serialized with concurrent inserts. connection default; Success: 'insert into t2 select i+5 from t1' doesn't allow concurrent inserts into 't1'. connection default; Success: 'insert into t2 values ((select i+5 from t1 where i = 4))' doesn't allow concurrent inserts into 't1'. # # 2.7 LOAD DATA with a subquery. # # The above is true for this statement as well. connection default; Success: 'load data infile '../../std_data/rpl_loaddata.dat' into table t2 (@a, @b) set j= @b + (select i from t1 where i = 1)' doesn't allow concurrent inserts into 't1'. # # 2.8 REPLACE with a subquery. # # Same is true for this statement as well. # Suppress warnings for REPLACE ... SELECT connection default; Success: 'replace into t2 select i+5 from t1' doesn't allow concurrent inserts into 't1'. connection default; Success: 'replace into t2 values ((select i+5 from t1 where i = 4))' doesn't allow concurrent inserts into 't1'. # # 2.9 SELECT with a subquery. # # Strong locks are not necessary as this statement is not written # to the binary log and thanks to how MyISAM works this statement # sees a version of the table prior to the concurrent insert. connection default; Success: 'select * from t2 where j in (select i from t1)' allows concurrent inserts into 't1'. # # 2.10 SET with a subquery. # # The same is true for this statement as well. connection default; Success: 'set @a:= (select i from t1 where i = 1)' allows concurrent inserts into 't1'. # # 2.11 SHOW with a subquery. # # And for this statement too. connection default; Success: 'show tables from test where Tables_in_test = 't2' and (select i from t1 where i = 1)' allows concurrent inserts into 't1'. connection default; Success: 'show columns from t2 where (select i from t1 where i = 1)' allows concurrent inserts into 't1'. # # 2.12 UPDATE with a subquery. # # Has to take a strong lock on the table being read as # this statement is written to the binary log and therefore # should be serialized with concurrent inserts. connection default; Success: 'update t2 set j= j-10 where j in (select i from t1)' doesn't allow concurrent inserts into 't1'. # # 2.13 MULTI-UPDATE with a subquery. # # Same is true for this statement as well. connection default; Success: 'update t2, t3 set j= j -10 where j=k and j in (select i from t1)' doesn't allow concurrent inserts into 't1'. # # 3. Statements which read tables through a view. # # # 3.1 SELECT statement which uses some table through a view. # # Since this statement is not written to the binary log and # an old version of the table is accessible thanks to how MyISAM # handles concurrent insert, no locking is necessary. connection default; Success: 'select * from v1' allows concurrent inserts into 't1'. connection default; Success: 'select * from v2' allows concurrent inserts into 't1'. connection default; Success: 'select * from t2 where j in (select i from v1)' allows concurrent inserts into 't1'. connection default; Success: 'select * from t3 where k in (select j from v2)' allows concurrent inserts into 't1'. # # 3.2 Statements which modify a table and use views. # # Since such statements are going to be written to the binary # log they need to be serialized against concurrent statements # and therefore should take strong locks on the data read. connection default; Success: 'update t2 set j= j-10 where j in (select i from v1)' doesn't allow concurrent inserts into 't1'. connection default; Success: 'update t3 set k= k-10 where k in (select j from v2)' doesn't allow concurrent inserts into 't1'. connection default; Success: 'update t2, v1 set j= j-10 where j = i' doesn't allow concurrent inserts into 't1'. connection default; Success: 'update v2 set j= j-10 where j = 3' doesn't allow concurrent inserts into 't1'. # # 4. Statements which read tables through stored functions. # # # 4.1 SELECT/SET with a stored function which does not # modify data and uses SELECT in its turn. # # There is no need to take strong locks on the table # being selected from in SF as the call to such function # won't get into the binary log. connection default; Success: 'select f1()' allows concurrent inserts into 't1'. connection default; Success: 'set @a:= f1()' allows concurrent inserts into 't1'. # # 4.2 INSERT (or other statement which modifies data) with # a stored function which does not modify data and uses # SELECT. # # Since such statement is written to the binary log it should # be serialized with concurrent statements affecting the data # it uses. Therefore it should take strong lock on the data # it reads. connection default; Success: 'insert into t2 values (f1() + 5)' doesn't allow concurrent inserts into 't1'. # # 4.3 SELECT/SET with a stored function which # reads and modifies data. # # Since a call to such function is written to the binary log, # it should be serialized with concurrent statements affecting # the data it uses. Hence, a strong lock on the data read # should be taken. connection default; Success: 'select f2()' doesn't allow concurrent inserts into 't1'. connection default; Success: 'set @a:= f2()' doesn't allow concurrent inserts into 't1'. # # 4.4. SELECT/SET with a stored function which does not # modify data and reads a table through subselect # in a control construct. # # Call to this function won't get to the # binary log and thus no strong lock is needed. connection default; Success: 'select f3()' allows concurrent inserts into 't1'. connection default; Success: 'set @a:= f3()' allows concurrent inserts into 't1'. connection default; Success: 'select f4()' allows concurrent inserts into 't1'. connection default; Success: 'set @a:= f4()' allows concurrent inserts into 't1'. # # 4.5. INSERT (or other statement which modifies data) with # a stored function which does not modify data and reads # the table through a subselect in one of its control # constructs. # # Since such statement is written to the binary log it should # be serialized with concurrent statements affecting data it # uses. Therefore it should take a strong lock on the data # it reads. connection default; Success: 'insert into t2 values (f3() + 5)' doesn't allow concurrent inserts into 't1'. connection default; Success: 'insert into t2 values (f4() + 6)' doesn't allow concurrent inserts into 't1'. # # 4.6 SELECT/SET which uses a stored function with # DML which reads a table via a subquery. # # Since call to such function is written to the binary log # it should be serialized with concurrent statements. # Hence reads should take a strong lock. connection default; Success: 'select f5()' doesn't allow concurrent inserts into 't1'. connection default; Success: 'set @a:= f5()' doesn't allow concurrent inserts into 't1'. # # 4.7 SELECT/SET which uses a stored function which # doesn't modify data and reads tables through # a view. # # Calls to such functions won't get into # the binary log and thus don't need strong # locks. connection default; Success: 'select f6()' allows concurrent inserts into 't1'. connection default; Success: 'set @a:= f6()' allows concurrent inserts into 't1'. connection default; Success: 'select f7()' allows concurrent inserts into 't1'. connection default; Success: 'set @a:= f7()' allows concurrent inserts into 't1'. # # 4.8 INSERT which uses stored function which # doesn't modify data and reads a table # through a view. # # Since such statement is written to the binary log and # should be serialized with concurrent statements affecting # the data it uses. Therefore it should take a strong lock on # the table it reads. connection default; Success: 'insert into t3 values (f6() + 5)' doesn't allow concurrent inserts into 't1'. connection default; Success: 'insert into t3 values (f7() + 5)' doesn't allow concurrent inserts into 't1'. # # 4.9 SELECT which uses a stored function which # modifies data and reads tables through a view. # # Since a call to such function is written to the binary log # it should be serialized with concurrent statements. # Hence, reads should take strong locks. connection default; Success: 'select f8()' doesn't allow concurrent inserts into 't1'. connection default; Success: 'select f9()' doesn't allow concurrent inserts into 't1'. # # 4.10 SELECT which uses a stored function which doesn't modify # data and reads a table indirectly, by calling another # function. # # Calls to such functions won't get into the binary # log and thus don't need to acquire strong locks. connection default; Success: 'select f10()' allows concurrent inserts into 't1'. # # 4.11 INSERT which uses a stored function which doesn't modify # data and reads a table indirectly, by calling another # function. # # Since such statement is written to the binary log, it should # be serialized with concurrent statements affecting the data it # uses. Therefore it should take strong locks on data it reads. connection default; Success: 'insert into t2 values (f10() + 5)' doesn't allow concurrent inserts into 't1'. # # 4.12 SELECT which uses a stored function which modifies # data and reads a table indirectly, by calling another # function. # # Since a call to such function is written to the binary log # it should be serialized from concurrent statements. # Hence, read should take a strong lock. connection default; Success: 'select f11()' doesn't allow concurrent inserts into 't1'. # # 4.13 SELECT that reads a table through a subquery passed # as a parameter to a stored function which modifies # data. # # Even though a call to this function is written to the # binary log, values of its parameters are written as literals. # So there is no need to acquire strong locks for tables used in # the subquery. connection default; Success: 'select f12((select i+10 from t1 where i=1))' allows concurrent inserts into 't1'. # # 4.14 INSERT that reads a table via a subquery passed # as a parameter to a stored function which doesn't # modify data. # # Since this statement is written to the binary log it should # be serialized with concurrent statements affecting the data it # uses. Therefore it should take strong locks on the data it reads. connection default; Success: 'insert into t2 values (f13((select i+10 from t1 where i=1)))' doesn't allow concurrent inserts into 't1'. # # 4.15 SELECT/SET with a stored function which # inserts data into a temporary table using # SELECT on t1. # # Since this statement is written to the binary log it should # be serialized with concurrent statements affecting the data it # uses. Therefore it should take strong locks on the data it reads. connection default; Success: 'select f16()' doesn't allow concurrent inserts into 't1'. connection default; Success: 'set @a:= f16()' doesn't allow concurrent inserts into 't1'. # # 4.16 SELECT/SET with a stored function which call procedure # which inserts data into a temporary table using # SELECT on t1. # # Since this statement is written to the binary log it should # be serialized with concurrent statements affecting the data it # uses. Therefore it should take strong locks on the data it reads. connection default; Success: 'select f17()' doesn't allow concurrent inserts into 't1'. connection default; Success: 'set @a:= f17()' doesn't allow concurrent inserts into 't1'. # # 5. Statements that read tables through stored procedures. # # # 5.1 CALL statement which reads a table via SELECT. # # Since neither this statement nor its components are # written to the binary log, there is no need to take # strong locks on the data it reads. connection default; Success: 'call p2(@a)' allows concurrent inserts into 't1'. # # 5.2 Function that modifies data and uses CALL, # which reads a table through SELECT. # # Since a call to such function is written to the binary # log, it should be serialized with concurrent statements. # Hence, in this case reads should take strong locks on data. connection default; Success: 'select f14()' doesn't allow concurrent inserts into 't1'. # # 5.3 SELECT that calls a function that doesn't modify data and # uses a CALL statement that reads a table via SELECT. # # Calls to such functions won't get into the binary # log and thus don't need to acquire strong locks. connection default; Success: 'select f15()' allows concurrent inserts into 't1'. # # 5.4 INSERT which calls function which doesn't modify data and # uses CALL statement which reads table through SELECT. # # Since such statement is written to the binary log it should # be serialized with concurrent statements affecting data it # uses. Therefore it should take strong locks on data it reads. connection default; Success: 'insert into t2 values (f15()+5)' doesn't allow concurrent inserts into 't1'. # # 6. Statements that use triggers. # # # 6.1 Statement invoking a trigger that reads table via SELECT. # # Since this statement is written to the binary log it should # be serialized with concurrent statements affecting the data # it uses. Therefore, it should take strong locks on the data # it reads. connection default; Success: 'insert into t4 values (2)' doesn't allow concurrent inserts into 't1'. # # 6.2 Statement invoking a trigger that reads table through # a subquery in a control construct. # # The above is true for this statement as well. connection default; Success: 'update t4 set l= 2 where l = 1' doesn't allow concurrent inserts into 't1'. # # 6.3 Statement invoking a trigger that reads a table through # a view. # # And for this statement. connection default; Success: 'delete from t4 where l = 1' doesn't allow concurrent inserts into 't1'. # # 6.4 Statement invoking a trigger that reads a table through # a stored function. # # And for this statement. connection default; Success: 'insert into t5 values (2)' doesn't allow concurrent inserts into 't1'. # # 6.5 Statement invoking a trigger that reads a table through # stored procedure. # # And for this statement. connection default; Success: 'update t5 set l= 2 where l = 1' doesn't allow concurrent inserts into 't1'. # Clean-up. drop function f1; drop function f2; drop function f3; drop function f4; drop function f5; drop function f6; drop function f7; drop function f8; drop function f9; drop function f10; drop function f11; drop function f12; drop function f13; drop function f14; drop function f15; drop function f16; drop function f17; drop view v1, v2; drop procedure p1; drop procedure p2; drop procedure p3; drop table t1, t2, t3, t4, t5; disconnect con1; disconnect con2; set @@global.concurrent_insert= @old_concurrent_insert; # # Bug#50821 Deadlock between LOCK TABLES and ALTER TABLE # DROP TABLE IF EXISTS t1, t2; CREATE TABLE t1(id INT); CREATE TABLE t2(id INT); connect con2, localhost, root; START TRANSACTION; SELECT * FROM t1; id connection default; # Sending: ALTER TABLE t1 ADD COLUMN j INT; connection con2; # This used to cause a deadlock. INSERT INTO t2 SELECT * FROM t1; COMMIT; connection default; # Reaping ALTER TABLE t1 ADD COLUMN j INT DROP TABLE t1, t2; disconnect con2; # # Bug#51391 Deadlock involving events during rqg_info_schema test # CREATE EVENT e1 ON SCHEDULE EVERY 5 HOUR DO SELECT 1; Warnings: Warning 1105 Event scheduler is switched off, use SET GLOBAL event_scheduler=ON to enable it. CREATE EVENT e2 ON SCHEDULE EVERY 5 HOUR DO SELECT 2; Warnings: Warning 1105 Event scheduler is switched off, use SET GLOBAL event_scheduler=ON to enable it. connect con1, localhost, root; SET DEBUG_SYNC="before_lock_tables_takes_lock SIGNAL drop WAIT_FOR query"; # Sending: DROP EVENT e1;; connection default; SET DEBUG_SYNC="now WAIT_FOR drop"; SELECT name FROM mysql.event, INFORMATION_SCHEMA.GLOBAL_VARIABLES WHERE definer = VARIABLE_VALUE; name SET DEBUG_SYNC="now SIGNAL query"; connection con1; # Reaping: DROP EVENT t1 disconnect con1; connection default; DROP EVENT e2; SET DEBUG_SYNC="RESET"; # # Bug#57130 crash in Item_field::print during SHOW CREATE TABLE or VIEW # DROP TABLE IF EXISTS t1; DROP VIEW IF EXISTS v1; DROP FUNCTION IF EXISTS f1; CREATE TABLE t1(a INT); CREATE FUNCTION f1() RETURNS INTEGER RETURN 1; CREATE VIEW v1 AS SELECT * FROM t1 WHERE f1() = 1; DROP FUNCTION f1; connect con2, localhost, root; connect con1, localhost, root; SET DEBUG_SYNC= 'open_tables_after_open_and_process_table SIGNAL opened WAIT_FOR dropped EXECUTE 2'; # Sending: SHOW CREATE VIEW v1; connection con2; SET DEBUG_SYNC= 'now WAIT_FOR opened'; SET DEBUG_SYNC= 'now SIGNAL dropped'; SET DEBUG_SYNC= 'now WAIT_FOR opened'; # Sending: FLUSH TABLES t1; connection default; # Waiting for FLUSH TABLES to be blocked. SET DEBUG_SYNC= 'now SIGNAL dropped'; connection con1; # Reaping: SHOW CREATE VIEW v1 View Create View character_set_client collation_connection v1 CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `v1` AS select `t1`.`a` AS `a` from `t1` where `f1`() = 1 latin1 latin1_swedish_ci Warnings: Warning 1356 View 'test.v1' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them connection con2; # Reaping: FLUSH TABLES connection default; SET DEBUG_SYNC= 'RESET'; DROP VIEW v1; DROP TABLE t1; disconnect con1; disconnect con2; # # Bug#28587 SELECT is blocked by INSERT waiting on read lock, even with low_priority_updates # set low_priority_updates=1; drop table if exists t1; drop table if exists t2; set debug_sync='RESET'; create table t1 (a int, b int, unique key t1$a (a)); create table t2 (j int, k int); set debug_sync='after_lock_tables_takes_lock SIGNAL parked WAIT_FOR go'; # Sending: insert into t2 select * from t1;; connect update,localhost,root,,; connection update; set debug_sync='now WAIT_FOR parked'; set low_priority_updates=1; show variables like 'low_priority_updates'; Variable_name Value low_priority_updates ON insert into t1 values (1, 2) ON DUPLICATE KEY UPDATE b = 2;; connect select,localhost,root,,; select * from t1; a b set debug_sync='now SIGNAL go'; connection default; disconnect update; disconnect select; # Reaping INSERT SELECT drop tables t1, t2; set low_priority_updates=default; set debug_sync='RESET'; # # Additional test coverage for LOCK TABLES ... READ LOCAL # for InnoDB tables. # # Check that we correctly handle deadlocks which can occur # during metadata lock upgrade which happens when one tries # to use LOCK TABLES ... READ LOCAL for InnoDB tables. CREATE TABLE t1 (i INT) ENGINE=InnoDB; CREATE TABLE t2 (j INT) ENGINE=InnoDB; # Execute LOCK TABLE READ LOCK which will pause after acquiring # SR metadata lock and before upgrading it to SRO lock. SET DEBUG_SYNC="after_open_table_mdl_shared SIGNAL locked WAIT_FOR go"; # Sending: LOCK TABLE t1 READ LOCAL; connect con1, localhost, root; SET DEBUG_SYNC="now WAIT_FOR locked"; # Execute RENAME TABLE which will try to acquire X lock. # Sending: RENAME TABLE t1 TO t3, t2 TO t1, t3 TO t2; connect con2, localhost, root; # Wait until RENAME TABLE is blocked. # Resume LOCK TABLE statement. It should try to # upgrade SR lock to SRO lock which will create # deadlock due to presence of pending X lock. # Deadlock should be detected and LOCK TABLES should # release its MDL and retry opening of tables. SET DEBUG_SYNC="now SIGNAL go"; connection con1; # RENAME TABLE should be able to complete. Reap it. connection default; # Reap LOCK TABLES. # Check that we see new version of table. SELECT * FROM t1; j UNLOCK TABLES; # Clean-up. SET DEBUG_SYNC="RESET"; disconnect con1; disconnect con2; DROP TABLES t1, t2;