Commit a49f5cae authored by unknown's avatar unknown
Browse files

Bug#4118: multi-table UPDATE takes WRITE lock on read table 

  Ensures that WRITE lock is not obtained on all tables referenced.


mysql-test/r/lock_multi.result:
  Bug#4118
    New test for multi-update locking
mysql-test/r/multi_update.result:
  Bug#4118
    Fix test
mysql-test/t/lock_multi.test:
  Bug#4118
    New test for multi-update locking
mysql-test/t/multi_update.test:
  Bug#4118
    Fix test
sql/sql_parse.cc:
  Bug#4118
    Split multi-update to its own case statement in sql_parse.cc
sql/sql_update.cc:
  Bug#4118
    Overview of locking checking:    
      1. Open and acquire READ lock
      2. Check to see which tables need WRITE lock
      3. Unlock tables and relock
sql/sql_yacc.yy:
  Bug#4118
    Split multi-update to its own case statement in sql_parse.cc
parent 79950521

mysql-test/r/lock_multi.result

+12 −0
Original line number Diff line number Diff line
@@ -17,6 +17,18 @@ unlock tables; 
n

1

drop table t1;

create table t1 (a int, b int);

create table t2 (c int, d int);

insert into t1 values(1,1);

insert into t1 values(2,2);

insert into t2 values(1,2);

lock table t1 read;

 update t1,t2 set c=a where b=d;

select c from t2;

c

2

drop table t1;

drop table t2;

create table t1 (a int);

create table t2 (a int);

lock table t1 write, t2 write;

mysql-test/r/multi_update.result

+0 −1
Original line number Diff line number Diff line
@@ -151,7 +151,6 @@ Table 't2' was locked with a READ lock and can't be updated 
UPDATE t1,t2 SET t1.d=t2.d,t2.d=30 WHERE t1.n=t2.n;

Table 't2' was locked with a READ lock and can't be updated

UPDATE t1,t2 SET t1.d=t2.d WHERE t1.n=t2.n;

Table 't2' was locked with a READ lock and can't be updated

unlock tables;

LOCK TABLES t1 write, t2 write;

UPDATE t1,t2 SET t1.d=t2.d WHERE t1.n=t2.n;

mysql-test/t/lock_multi.test

+24 −0
Original line number Diff line number Diff line
@@ -50,6 +50,30 @@ connection reader; 
reap;

drop table t1;



#

# Test problem when using locks with multi-updates

# It should not block when multi-update is reading on a read-locked table

#



connection locker;

create table t1 (a int, b int);

create table t2 (c int, d int);

insert into t1 values(1,1);

insert into t1 values(2,2);

insert into t2 values(1,2);

lock table t1 read;

connection writer;

--sleep 2

send update t1,t2 set c=a where b=d;

connection reader;

--sleep 2

select c from t2;

connection writer;

reap;

connection locker;

drop table t1;

drop table t2;



#

# Test problem when using locks on many tables and droping a table that

# is to-be-locked by another thread

mysql-test/t/multi_update.test

+0 −2
Original line number Diff line number Diff line
@@ -151,8 +151,6 @@ LOCK TABLES t1 write, t2 read; 
DELETE t1.*, t2.* FROM t1,t2 where t1.n=t2.n;

--error 1099

UPDATE t1,t2 SET t1.d=t2.d,t2.d=30 WHERE t1.n=t2.n;

# The following should be fixed to not give an error

--error 1099

UPDATE t1,t2 SET t1.d=t2.d WHERE t1.n=t2.n;

unlock tables;

LOCK TABLES t1 write, t2 write;

sql/sql_parse.cc

+17 −12
Original line number Diff line number Diff line
@@ -1927,8 +1927,6 @@ mysql_execute_command(void) 
      send_error(&thd->net,ER_WRONG_VALUE_COUNT);

      DBUG_VOID_RETURN;

    }

    if (select_lex->table_list.elements == 1)

    {

    if (check_one_table_access(thd, UPDATE_ACL, tables, 0))

      goto error; /* purecov: inspected */
@@ -1940,8 +1938,15 @@ mysql_execute_command(void) 
		      (ORDER *) select_lex->order_list.first,

		      select_lex->select_limit,

		      lex->duplicates);

    break;

  case SQLCOM_MULTI_UPDATE:

    if (check_db_used(thd,tables))

      goto error;

    if (select_lex->item_list.elements != lex->value_list.elements)

    {

      send_error(&thd->net,ER_WRONG_VALUE_COUNT);

      DBUG_VOID_RETURN;

    }

    else

    {

      const char *msg= 0;

      TABLE_LIST *table;