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From:Ingo Struewing Date:July 20 2009 12:48pm
Subject:bzr commit into mysql-5.4 branch (ingo.struewing:2847) Bug#20667
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#At file:///home2/mydev/bzrroot/mysql-6.0-bug20667-2/ based on revid:hema@stripped

 2847 Ingo Struewing	2009-07-20
      Bug#20667 - Truncate table fails for a write locked table
      
      TRUNCATE TABLE was not allowed under LOCK TABLES.
      
      The patch removes this restriction. mysql_truncate()
      does now handle that case.
     @ mysql-test/r/merge.result
        Bug#20667 - Truncate table fails for a write locked table
        Updated test result.
     @ mysql-test/r/truncate.result
        Bug#20667 - Truncate table fails for a write locked table
        Updated test result.
     @ mysql-test/t/merge.test
        Bug#20667 - Truncate table fails for a write locked table
        Updated test case due to now working TRUNCATE under LOCK TABLES.
        Added some SELECTs to show that child tables are truncated.
     @ mysql-test/t/truncate.test
        Bug#20667 - Truncate table fails for a write locked table
        Added test.
     @ sql/sql_delete.cc
        Bug#20667 - Truncate table fails for a write locked table
        Added branches for thd->locked_tables_mode.
     @ sql/sql_parse.cc
        Bug#20667 - Truncate table fails for a write locked table
        Deleted rejection of TRUNCATE in case of LOCK TABLES.

    modified:
      mysql-test/r/merge.result
      mysql-test/r/truncate.result
      mysql-test/t/merge.test
      mysql-test/t/truncate.test
      sql/sql_delete.cc
      sql/sql_parse.cc
=== modified file 'mysql-test/r/merge.result'
--- a/mysql-test/r/merge.result	2009-04-22 10:02:28 +0000
+++ b/mysql-test/r/merge.result	2009-07-20 12:48:11 +0000
@@ -1053,18 +1053,21 @@ c1
 LOCK TABLE t1 WRITE, t2 WRITE, t3 WRITE;
 INSERT INTO t1 VALUES (1);
 TRUNCATE TABLE t3;
-ERROR HY000: Can't execute the given command because you have active locked tables or an active transaction
 SELECT * FROM t3;
 c1
-1
-2
+UNLOCK TABLES;
+SELECT * FROM t1;
+c1
+SELECT * FROM t2;
+c1
 #
 # Truncate child table under locked tables.
+LOCK TABLE t1 WRITE, t2 WRITE, t3 WRITE;
+INSERT INTO t1 VALUES (1);
+INSERT INTO t2 VALUES (2);
 TRUNCATE TABLE t1;
-ERROR HY000: Can't execute the given command because you have active locked tables or an active transaction
 SELECT * FROM t3;
 c1
-1
 2
 UNLOCK TABLES;
 DROP TABLE t1, t2, t3;
@@ -1096,18 +1099,24 @@ INSERT INTO t1 VALUES (1);
 CREATE TABLE t4 (c1 INT, INDEX(c1));
 LOCK TABLE t4 WRITE;
 TRUNCATE TABLE t3;
-ERROR HY000: Can't execute the given command because you have active locked tables or an active transaction
 SELECT * FROM t3;
 c1
-1
-2
+SELECT * FROM t1;
+c1
+SELECT * FROM t2;
+c1
 #
 # Truncate temporary child table under locked tables.
+INSERT INTO t1 VALUES (1);
+INSERT INTO t2 VALUES (2);
 TRUNCATE TABLE t1;
-ERROR HY000: Can't execute the given command because you have active locked tables or an active transaction
 SELECT * FROM t3;
 c1
-1
+2
+SELECT * FROM t1;
+c1
+SELECT * FROM t2;
+c1
 2
 UNLOCK TABLES;
 DROP TABLE t1, t2, t3, t4;

=== modified file 'mysql-test/r/truncate.result'
--- a/mysql-test/r/truncate.result	2007-04-17 10:32:01 +0000
+++ b/mysql-test/r/truncate.result	2009-07-20 12:48:11 +0000
@@ -60,3 +60,28 @@ truncate table v1;
 ERROR 42S02: Table 'test.v1' doesn't exist
 drop view v1;
 drop table t1;
+#
+# Bug#20667 - Truncate table fails for a write locked table
+#
+CREATE TABLE t1 (c1 INT) ENGINE=MyISAM;
+LOCK TABLE t1 WRITE;
+INSERT INTO t1 VALUES (1);
+SELECT * FROM t1;
+c1
+1
+TRUNCATE TABLE t1;
+SELECT * FROM t1;
+c1
+UNLOCK TABLES;
+LOCK TABLE t1 READ;
+TRUNCATE TABLE t1;
+ERROR HY000: Table 't1' was locked with a READ lock and can't be updated
+UNLOCK TABLES;
+CREATE TABLE t2 (c1 INT) ENGINE=MyISAM;
+LOCK TABLE t2 WRITE;
+TRUNCATE TABLE t1;
+ERROR HY000: Table 't1' was not locked with LOCK TABLES
+UNLOCK TABLES;
+DROP TABLE t1;
+DROP TABLE t2;
+# End of 6.0 tests

=== modified file 'mysql-test/t/merge.test'
--- a/mysql-test/t/merge.test	2009-04-22 10:02:28 +0000
+++ b/mysql-test/t/merge.test	2009-07-20 12:48:11 +0000
@@ -688,12 +688,16 @@ SELECT * FROM t3;
 --echo # Truncate MERGE table under locked tables.
 LOCK TABLE t1 WRITE, t2 WRITE, t3 WRITE;
 INSERT INTO t1 VALUES (1);
---error ER_LOCK_OR_ACTIVE_TRANSACTION
 TRUNCATE TABLE t3;
 SELECT * FROM t3;
+UNLOCK TABLES;
+SELECT * FROM t1;
+SELECT * FROM t2;
 --echo #
 --echo # Truncate child table under locked tables.
---error ER_LOCK_OR_ACTIVE_TRANSACTION
+LOCK TABLE t1 WRITE, t2 WRITE, t3 WRITE;
+INSERT INTO t1 VALUES (1);
+INSERT INTO t2 VALUES (2);
 TRUNCATE TABLE t1;
 SELECT * FROM t3;
 UNLOCK TABLES;
@@ -719,14 +723,18 @@ SELECT * FROM t3;
 INSERT INTO t1 VALUES (1);
 CREATE TABLE t4 (c1 INT, INDEX(c1));
 LOCK TABLE t4 WRITE;
---error ER_LOCK_OR_ACTIVE_TRANSACTION
 TRUNCATE TABLE t3;
 SELECT * FROM t3;
+SELECT * FROM t1;
+SELECT * FROM t2;
 --echo #
 --echo # Truncate temporary child table under locked tables.
---error ER_LOCK_OR_ACTIVE_TRANSACTION
+INSERT INTO t1 VALUES (1);
+INSERT INTO t2 VALUES (2);
 TRUNCATE TABLE t1;
 SELECT * FROM t3;
+SELECT * FROM t1;
+SELECT * FROM t2;
 UNLOCK TABLES;
 DROP TABLE t1, t2, t3, t4;
 

=== modified file 'mysql-test/t/truncate.test'
--- a/mysql-test/t/truncate.test	2007-04-17 10:32:01 +0000
+++ b/mysql-test/t/truncate.test	2009-07-20 12:48:11 +0000
@@ -69,3 +69,29 @@ drop table t1;
 
 # End of 5.0 tests
 
+--echo #
+--echo # Bug#20667 - Truncate table fails for a write locked table
+--echo #
+CREATE TABLE t1 (c1 INT) ENGINE=MyISAM;
+LOCK TABLE t1 WRITE;
+INSERT INTO t1 VALUES (1);
+SELECT * FROM t1;
+TRUNCATE TABLE t1;
+SELECT * FROM t1;
+UNLOCK TABLES;
+#
+LOCK TABLE t1 READ;
+--error ER_TABLE_NOT_LOCKED_FOR_WRITE
+TRUNCATE TABLE t1;
+UNLOCK TABLES;
+#
+CREATE TABLE t2 (c1 INT) ENGINE=MyISAM;
+LOCK TABLE t2 WRITE;
+--error ER_TABLE_NOT_LOCKED
+TRUNCATE TABLE t1;
+UNLOCK TABLES;
+DROP TABLE t1;
+DROP TABLE t2;
+
+--echo # End of 6.0 tests
+

=== modified file 'sql/sql_delete.cc'
--- a/sql/sql_delete.cc	2009-06-19 09:28:44 +0000
+++ b/sql/sql_delete.cc	2009-07-20 12:48:11 +0000
@@ -1084,6 +1084,12 @@ bool mysql_truncate(THD *thd, TABLE_LIST
   bool error;
   uint path_length;
   MDL_request *mdl_request= NULL;
+  /*
+    Is set if we're under LOCK TABLES, and used
+    to downgrade the exclusive lock after the
+    table was truncated.
+  */
+  MDL_ticket *mdl_ticket= NULL;
   Ha_global_schema_lock_guard global_schema_lock_guard(thd);
   DBUG_ENTER("mysql_truncate");
 
@@ -1129,6 +1135,12 @@ bool mysql_truncate(THD *thd, TABLE_LIST
   if (!dont_send_ok)
   {
     enum legacy_db_type table_type;
+    /*
+      FIXME: Code of TRUNCATE breaks the meta-data
+      locking protocol since it tries to find out the table storage
+      engine and therefore accesses table in some way without holding
+      any kind of meta-data lock.
+    */
     mysql_frm_type(thd, path, &table_type);
     if (table_type == DB_TYPE_UNKNOWN)
     {
@@ -1143,24 +1155,47 @@ bool mysql_truncate(THD *thd, TABLE_LIST
 
     if (table_type == DB_TYPE_NDBCLUSTER)
       global_schema_lock_guard.lock();
-    /*
-      FIXME: Actually code of TRUNCATE breaks meta-data locking protocol since
-             tries to get table enging and therefore accesses table in some way
-             without holding any kind of meta-data lock.
-    */
-    mdl_request= MDL_request::create(0, table_list->db,
-                                     table_list->table_name, thd->mem_root);
-    mdl_request->set_type(MDL_EXCLUSIVE);
-    thd->mdl_context.add_request(mdl_request);
-    if (thd->mdl_context.acquire_exclusive_locks())
+
+    mysql_ha_rm_tables(thd, table_list);
+
+    if (thd->locked_tables_mode)
     {
-      thd->mdl_context.remove_request(mdl_request);
-      DBUG_RETURN(TRUE);
+      if (!(table= find_write_locked_table(thd->open_tables, table_list->db,
+                                           table_list->table_name)))
+        DBUG_RETURN(TRUE);
+      mdl_ticket= table->mdl_ticket;
+      if (wait_while_table_is_used(thd, table, HA_EXTRA_FORCE_REOPEN))
+        goto end;
+      close_all_tables_for_name(thd, table->s, FALSE);
+    }
+    else
+    {
+      /*
+        Even though we could use the previous execution branch
+        here just as well, we must not try to open the table: 
+        MySQL manual documents that TRUNCATE can be used to 
+        repair a damaged table, i.e. a table that can not be
+        fully "opened". In particular MySQL manual says:
+
+        As long as the table format file tbl_name.frm  is valid,
+        the table can be re-created as an empty table with TRUNCATE
+        TABLE, even if the data or index files have become corrupted.
+      */
+
+      mdl_request= MDL_request::create(0, table_list->db,
+                                       table_list->table_name, thd->mem_root);
+      mdl_request->set_type(MDL_EXCLUSIVE);
+      thd->mdl_context.add_request(mdl_request);
+      if (thd->mdl_context.acquire_exclusive_locks())
+      {
+        thd->mdl_context.remove_request(mdl_request);
+        DBUG_RETURN(TRUE);
+      }
+      pthread_mutex_lock(&LOCK_open);
+      tdc_remove_table(thd, TDC_RT_REMOVE_ALL, table_list->db,
+                       table_list->table_name);
+      pthread_mutex_unlock(&LOCK_open);
     }
-    pthread_mutex_lock(&LOCK_open);
-    tdc_remove_table(thd, TDC_RT_REMOVE_ALL, table_list->db,
-                     table_list->table_name);
-    pthread_mutex_unlock(&LOCK_open);
   }
 
   /*
@@ -1178,6 +1213,12 @@ bool mysql_truncate(THD *thd, TABLE_LIST
 end:
   if (!dont_send_ok)
   {
+    if (thd->locked_tables_mode && thd->locked_tables_list.reopen_tables(thd))
+      thd->locked_tables_list.unlink_all_closed_tables();
+    /*
+      Even if we failed to reopen some tables,
+      the operation itself succeeded, write the binlog.
+    */
     if (!error)
     {
       /*
@@ -1192,14 +1233,8 @@ end:
       thd->mdl_context.release_lock(mdl_request->ticket);
       thd->mdl_context.remove_request(mdl_request);
     }
-  }
-  else if (error)
-  {
-    if (mdl_request)
-    {
-      thd->mdl_context.release_lock(mdl_request->ticket);
-      thd->mdl_context.remove_request(mdl_request);
-    }
+    if (mdl_ticket)
+      mdl_ticket->downgrade_exclusive_lock();
   }
   DBUG_RETURN(error);
 

=== modified file 'sql/sql_parse.cc'
--- a/sql/sql_parse.cc	2009-07-10 12:31:32 +0000
+++ b/sql/sql_parse.cc	2009-07-20 12:48:11 +0000
@@ -3316,7 +3316,7 @@ end_with_restore_list:
       Don't allow this within a transaction because we want to use
       re-generate table
     */
-    if (thd->locked_tables_mode || thd->active_transaction())
+    if (thd->active_transaction())
     {
       my_message(ER_LOCK_OR_ACTIVE_TRANSACTION,
                  ER(ER_LOCK_OR_ACTIVE_TRANSACTION), MYF(0));


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bzr commit into mysql-5.4 branch (ingo.struewing:2847) Bug#20667Ingo Struewing20 Jul
  • Re: bzr commit into mysql-5.4 branch (ingo.struewing:2847) Bug#20667Konstantin Osipov20 Jul