Bug#17942050:KILL OF TRUNCATE TABLE WILL LEAD TO BINARY LOG

WRITTEN WHILE ROWS REMAINS

Problem:
========
When truncate table fails while using transactional based
engines even though the operation errors out we still
continue and log it to binlog. Because of this master has
data but the truncate will be written to binary log which
will cause inconsistency.

Analysis:
========
Truncate table can happen either through drop and create of
table or by deleting rows. In the second case the existing
code is written in such a way that even if an error occurs
the truncate statement will always be binlogged. Which is not
correct.

Binlogging of TRUNCATE TABLE statement should check whether
truncate is executed "transactionally or not". If the table
is transaction based we log the TRUNCATE TABLE only on
successful completion.

If table is non transactional there are possibilities that on
error we could have partial changes done hence in such cases
we do log in spite of errors as some of the lines might have
been removed, so the statement has to be sent to slave.

Fix:
===
Using table handler whether truncate table is being executed
in transaction based mode or not is identified and statement
is binlogged accordingly.

mysql-test/suite/binlog/r/binlog_truncate_kill.result:
  Added test case to test the fix for Bug#17942050.
mysql-test/suite/binlog/t/binlog_truncate_kill.test:
  Added test case to test the fix for Bug#17942050.
sql/sql_truncate.cc:
  Check if truncation is successful or not and retun appropriate
  return values so that binlogging can be done based on that.
sql/sql_truncate.h:
  Added a new enum.

mysql-test/suite/binlog/r/binlog_truncate_kill.result

+RESET MASTER;
+connection default;
+CREATE TABLE t1(id INT AUTO_INCREMENT PRIMARY KEY, a INT, b INT) ENGINE=INNODB;
+INSERT INTO t1(a, b) VALUES(1,2),(2,4),(3,6),(4,8),(5,10);
+SET DEBUG_SYNC = "open_and_process_table signal truncate_before_lock wait_for forever";
+TRUNCATE t1;
+connect con1,localhost,root,,;
+SET DEBUG_SYNC = "now wait_for truncate_before_lock";
+SELECT ((@id := id) - id) FROM information_schema.processlist WHERE processlist.info LIKE '%TRUNCATE t1%' AND state LIKE '%open_and_process_table%';
+((@id := id) - id)
+0
+KILL QUERY @id;
+connection default;
+ERROR 70100: Query execution was interrupted
+connection con1;
+show binlog events from <binlog_start>;
+Log_name	Pos	Event_type	Server_id	End_log_pos	Info
+master-bin.000001	#	Query	#	#	use `test`; CREATE TABLE t1(id INT AUTO_INCREMENT PRIMARY KEY, a INT, b INT) ENGINE=INNODB
+master-bin.000001	#	Query	#	#	BEGIN
+master-bin.000001	#	Intvar	#	#	INSERT_ID=1
+master-bin.000001	#	Query	#	#	use `test`; INSERT INTO t1(a, b) VALUES(1,2),(2,4),(3,6),(4,8),(5,10)
+master-bin.000001	#	Xid	#	#	COMMIT /* XID */
+disconnect con1;
+connection default;
+SELECT * FROM t1;
+id	a	b
+1	1	2
+2	2	4
+3	3	6
+4	4	8
+5	5	10
+DROP TABLE t1;
+SET DEBUG_SYNC= 'RESET';

mysql-test/suite/binlog/t/binlog_truncate_kill.test

+###############################################################################
+# Bug#17942050:KILL OF TRUNCATE TABLE WILL LEAD TO BINARY LOG WRITTEN WHILE
+# ROWS REMAINS
+#
+# Problem:
+# ========
+# When truncate table fails while using transactional based engines even
+# though the operation errors out we still continue and log it to binlog.
+# Because of this master has data but the truncate will be written to binary
+# log which will cause inconsistency.
+#
+# Test:
+# =====
+# Make master to wait in "open_table" call during the execution of truncate
+# table command and kill the truncate table from other connection. This causes
+# open table to return an error saying truncate failed during open table. This
+# statement should not be binlogged.
+###############################################################################
+--source include/have_debug_sync.inc
+--source include/have_binlog_format_statement.inc
+RESET MASTER;
+--enable_connect_log
+--connection default
+CREATE TABLE t1(id INT AUTO_INCREMENT PRIMARY KEY, a INT, b INT) ENGINE=INNODB;
+INSERT INTO t1(a, b) VALUES(1,2),(2,4),(3,6),(4,8),(5,10);
+SET DEBUG_SYNC = "open_and_process_table signal truncate_before_lock wait_for forever";
+--send TRUNCATE t1
+
+connect(con1,localhost,root,,);
+SET DEBUG_SYNC = "now wait_for truncate_before_lock";
+# Wait for one connection to reach open_and_process_table.
+--let $show_statement= SHOW PROCESSLIST
+--let $field= State
+--let $condition= 'debug sync point: open_and_process_table';
+--source include/wait_show_condition.inc
+
+SELECT ((@id := id) - id) FROM information_schema.processlist WHERE processlist.info LIKE '%TRUNCATE t1%' AND state LIKE '%open_and_process_table%';
+# Test killing from mysql server
+KILL QUERY @id;
+
+connection default;
+--ERROR ER_QUERY_INTERRUPTED
+--reap
+
+connection con1;
+--source include/show_binlog_events.inc
+
+disconnect con1;
+--source include/wait_until_disconnected.inc
+connection default;
+
+SELECT * FROM t1;
+
+DROP TABLE t1;
+SET DEBUG_SYNC= 'RESET';
+--disable_connect_log

sql/sql_truncate.cc

-/* Copyright (c) 2010, 2011, Oracle and/or its affiliates. All rights reserved.
+/* Copyright (c) 2010, 2014, Oracle and/or its affiliates. All rights reserved.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -181,12 +181,19 @@ fk_truncate_illegal_if_parent(THD *thd, TABLE *table)
   @param  table_ref     Table list element for the table to be truncated.
   @param  is_tmp_table  True if element refers to a temp table.
 
-  @retval  0    Success.
-  @retval  > 0  Error code.
+  @retval TRUNCATE_OK   Truncate was successful and statement can be safely
+                        binlogged.
+  @retval TRUNCATE_FAILED_BUT_BINLOG Truncate failed but still go ahead with
+                        binlogging as in case of non transactional tables
+                        partial truncation is possible.
+
+  @retval TRUNCATE_FAILED_SKIP_BINLOG Truncate was not successful hence donot
+                        binlong the statement.
 */
 
-int Truncate_statement::handler_truncate(THD *thd, TABLE_LIST *table_ref,
-                                         bool is_tmp_table)
+enum Truncate_statement::truncate_result
+Truncate_statement::handler_truncate(THD *thd, TABLE_LIST *table_ref,
+                                     bool is_tmp_table)
 {
   int error= 0;
   uint flags;
@@ -228,16 +235,30 @@ int Truncate_statement::handler_truncate(THD *thd, TABLE_LIST *table_ref,
 
   /* Open the table as it will handle some required preparations. */
   if (open_and_lock_tables(thd, table_ref, FALSE, flags))
-    DBUG_RETURN(1);
+    DBUG_RETURN(TRUNCATE_FAILED_SKIP_BINLOG);
 
   /* Whether to truncate regardless of foreign keys. */
   if (! (thd->variables.option_bits & OPTION_NO_FOREIGN_KEY_CHECKS))
-    error= fk_truncate_illegal_if_parent(thd, table_ref->table);
+    if (fk_truncate_illegal_if_parent(thd, table_ref->table))
+      DBUG_RETURN(TRUNCATE_FAILED_SKIP_BINLOG);
 
-  if (!error && (error= table_ref->table->file->ha_truncate()))
+  error= table_ref->table->file->ha_truncate();
+  if (error)
+  {
     table_ref->table->file->print_error(error, MYF(0));
-
-  DBUG_RETURN(error);
+    /*
+      If truncate method is not implemented then we don't binlog the
+      statement. If truncation has failed in a transactional engine then also we
+      donot binlog the statment. Only in non transactional engine we binlog
+      inspite of errors.
+     */
+    if (error == HA_ERR_WRONG_COMMAND ||
+        table_ref->table->file->has_transactions())
+      DBUG_RETURN(TRUNCATE_FAILED_SKIP_BINLOG);
+    else
+      DBUG_RETURN(TRUNCATE_FAILED_BUT_BINLOG);
+  }
+  DBUG_RETURN(TRUNCATE_OK);
 }
 
 
@@ -470,10 +491,14 @@ bool Truncate_statement::truncate_table(THD *thd, TABLE_LIST *table_ref)
 
       /*
         All effects of a TRUNCATE TABLE operation are committed even if
-        truncation fails. Thus, the query must be written to the binary
-        log. The only exception is a unimplemented truncate method.
+        truncation fails in the case of non transactional tables. Thus, the
+        query must be written to the binary log. The only exception is a
+        unimplemented truncate method.
       */
-      binlog_stmt= !error || error != HA_ERR_WRONG_COMMAND;
+      if (error == TRUNCATE_OK || error == TRUNCATE_FAILED_BUT_BINLOG)
+        binlog_stmt= true;
+      else
+        binlog_stmt= false;
     }
 
     /*

sql/sql_truncate.h

 #ifndef SQL_TRUNCATE_INCLUDED
 #define SQL_TRUNCATE_INCLUDED
-/* Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
+/* Copyright (c) 2010, 2014, Oracle and/or its affiliates. All rights reserved.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -47,11 +47,17 @@ public:
   bool execute(THD *thd);
 
 protected:
+  enum truncate_result{
+    TRUNCATE_OK=0,
+    TRUNCATE_FAILED_BUT_BINLOG,
+    TRUNCATE_FAILED_SKIP_BINLOG
+  };
+
   /** Handle locking a base table for truncate. */
   bool lock_table(THD *, TABLE_LIST *, bool *);
 
   /** Truncate table via the handler method. */
-  int handler_truncate(THD *, TABLE_LIST *, bool);
+  enum truncate_result handler_truncate(THD *, TABLE_LIST *, bool);
 
   /**
     Optimized delete of all rows by doing a full regenerate of the table.