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

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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
This commit is contained in:
unknown
2004-10-03 00:20:47 +01:00
parent 799505216f
commit a49f5cae9a
7 changed files with 155 additions and 33 deletions
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106
sql/sql_update.cc
View File

@ -401,25 +401,101 @@ int mysql_multi_update(THD *thd,
int res;
multi_update *result;
TABLE_LIST *tl;
const bool locked= !(thd->locked_tables);
DBUG_ENTER("mysql_multi_update");
if ((res=open_and_lock_tables(thd,table_list)))
DBUG_RETURN(res);
thd->select_limit=HA_POS_ERROR;
/*
Ensure that we have update privilege for all tables and columns in the
SET part
*/
for (tl= table_list ; tl ; tl=tl->next)
for (;;)
{
TABLE *table= tl->table;
table->grant.want_privilege= (UPDATE_ACL & ~table->grant.privilege);
}
table_map update_map= 0;
int tnr= 0;
if ((res= open_tables(thd, table_list)))
DBUG_RETURN(res);
if (setup_fields(thd, table_list, *fields, 1, 0, 0))
DBUG_RETURN(-1);
/*
Only need to call lock_tables if (thd->locked_tables == NULL)
*/
if (locked && ((res= lock_tables(thd, table_list))))
DBUG_RETURN(res);
thd->select_limit=HA_POS_ERROR;
/*
Ensure that we have update privilege for all tables and columns in the
SET part
While we are here, initialize the table->map field.
*/
for (tl= table_list ; tl ; tl=tl->next)
{
TABLE *table= tl->table;
table->grant.want_privilege= (UPDATE_ACL & ~table->grant.privilege);
table->map= (table_map) 1 << (tnr++);
}
if (!setup_fields(thd, table_list, *fields, 1, 0, 0))
{
List_iterator_fast<Item> field_it(*fields);
Item_field *item;
while ((item= (Item_field *) field_it++))
update_map|= item->used_tables();
DBUG_PRINT("info",("update_map=0x%08x", update_map));
}
else
DBUG_RETURN(-1);
/*
Unlock the tables in preparation for relocking
*/
if (locked)
{
pthread_mutex_lock(&LOCK_open);
mysql_unlock_tables(thd, thd->lock);
thd->lock= 0;
pthread_mutex_unlock(&LOCK_open);
}
/*
Set the table locking strategy according to the update map
*/
for (tl= table_list ; tl ; tl=tl->next)
{
TABLE *table= tl->table;
if (update_map & table->map)
{
DBUG_PRINT("info",("setting table `%s` for update", tl->alias));
tl->lock_type= thd->lex.lock_option;
tl->updating= 1;
}
else
{
DBUG_PRINT("info",("setting table `%s` for read-only", tl->alias));
tl->lock_type= TL_READ;
tl->updating= 0;
}
if (locked)
tl->table->reginfo.lock_type= tl->lock_type;
}
/*
Relock the tables
*/
if (!(res=lock_tables(thd,table_list)))
break;
if (!locked)
DBUG_RETURN(res);
List_iterator_fast<Item> field_it(*fields);
Item_field *item;
while ((item= (Item_field *) field_it++))
/* item->cleanup(); XXX Use this instead in MySQL 4.1+ */
item->field= item->result_field= 0;
close_thread_tables(thd);
}
/*
Count tables and setup timestamp handling