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From:Luis Soares Date:December 6 2009 4:51am
Subject:bzr commit into mysql-5.1-bugteam branch (luis.soares:3247) Bug#49481
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#At file:///home/lsoares/Workspace/bzr/work/bugfixing/49482/mysql-5.1-bugteam/ based on revid:davi.arnaut@stripped

 3247 Luis Soares	2009-12-06
      BUG#49481: RBR: MyISAM and bit fields may cause slave to stop on delete: 
      cant find record
      
      BUG#49482: RBR: Replication may break on deletes when MyISAM tables + 
      char field are used
      
      When using MyISAM tables, despite the fact that the null bit is
      set for some fields, their old value is still in the row. This
      can cause the comparison of records to fail when the slave is
      doing an index or range scan.
      
      We fix this by avoiding memcmp for MyISAM tables when comparing
      records. Additionally, when comparing field by field, we first
      check if both fields are not null and if so, then we compare
      them. If just one field is null we return failure immediately. If
      both fields are null, we move on to the next field.

    added:
      mysql-test/suite/rpl/r/rpl_myisam_null_values.result
      mysql-test/suite/rpl/t/rpl_myisam_null_values.test
    modified:
      sql/log_event.cc
=== added file 'mysql-test/suite/rpl/r/rpl_myisam_null_values.result'
--- a/mysql-test/suite/rpl/r/rpl_myisam_null_values.result	1970-01-01 00:00:00 +0000
+++ b/mysql-test/suite/rpl/r/rpl_myisam_null_values.result	2009-12-06 04:51:12 +0000
@@ -0,0 +1,24 @@
+stop slave;
+drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t9;
+reset master;
+reset slave;
+drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t9;
+start slave;
+CREATE TABLE t1 (c1 BIT, c2 INT);
+INSERT INTO `t1` VALUES ( 1, 1 );
+UPDATE t1 SET c1=NULL where c2=1;
+Comparing tables master:test.t1 and slave:test.t1
+DELETE FROM t1 WHERE c2=1 LIMIT 1;
+Comparing tables master:test.t1 and slave:test.t1
+DROP TABLE t1;
+CREATE TABLE t1 (c1 CHAR);
+INSERT INTO t1 ( c1 ) VALUES ( 'w' ) ;
+SELECT * FROM t1;
+c1
+w
+# should trigger switch to row due to LIMIT
+UPDATE t1 SET c1=NULL WHERE c1='w' LIMIT 2;
+Comparing tables master:test.t1 and slave:test.t1
+DELETE FROM t1 LIMIT 2;
+Comparing tables master:test.t1 and slave:test.t1
+DROP TABLE t1;

=== added file 'mysql-test/suite/rpl/t/rpl_myisam_null_values.test'
--- a/mysql-test/suite/rpl/t/rpl_myisam_null_values.test	1970-01-01 00:00:00 +0000
+++ b/mysql-test/suite/rpl/t/rpl_myisam_null_values.test	2009-12-06 04:51:12 +0000
@@ -0,0 +1,53 @@
+# BUG#49481: RBR: MyISAM and bit fields may cause slave to stop on delete cant find record
+# BUG#49482: RBR: Replication may break on deletes when MyISAM tables + char field are used
+
+-- source include/master-slave.inc
+-- source include/have_binlog_format_mixed_or_row.inc
+
+-- connection master
+CREATE TABLE t1 (c1 BIT, c2 INT);
+INSERT INTO `t1` VALUES ( 1, 1 );
+UPDATE t1 SET c1=NULL where c2=1;
+-- sync_slave_with_master
+
+-- let $diff_table_1=master:test.t1
+-- let $diff_table_2=slave:test.t1
+-- source include/diff_tables.inc
+
+-- connection master
+DELETE FROM t1 WHERE c2=1 LIMIT 1;
+-- sync_slave_with_master
+
+-- let $diff_table_1=master:test.t1
+-- let $diff_table_2=slave:test.t1
+-- source include/diff_tables.inc
+
+-- connection master
+DROP TABLE t1;
+-- sync_slave_with_master
+
+-- connection master
+
+CREATE TABLE t1 (c1 CHAR);
+
+INSERT INTO t1 ( c1 ) VALUES ( 'w' ) ;
+SELECT * FROM t1;
+-- echo # should trigger switch to row due to LIMIT
+UPDATE t1 SET c1=NULL WHERE c1='w' LIMIT 2;
+-- sync_slave_with_master
+
+-- let $diff_table_1=master:test.t1
+-- let $diff_table_2=slave:test.t1
+-- source include/diff_tables.inc
+
+-- connection master
+DELETE FROM t1 LIMIT 2;
+-- sync_slave_with_master
+
+-- let $diff_table_1=master:test.t1
+-- let $diff_table_2=slave:test.t1
+-- source include/diff_tables.inc
+
+-- connection master
+DROP TABLE t1;
+-- sync_slave_with_master

=== modified file 'sql/log_event.cc'
--- a/sql/log_event.cc	2009-11-21 13:02:18 +0000
+++ b/sql/log_event.cc	2009-12-06 04:51:12 +0000
@@ -8708,6 +8708,20 @@ static bool record_compare(TABLE *table)
     }
   }
 
+  /**
+    Check if we are using MyISAM.
+
+    If this is a myisam table, then we cannot do a memcmp
+    right away because for some nulled fields there can still
+    be old values in the row (null bits for bit fields or values
+    for char like fields) despite the fact that the null bit is
+    set. As such, plain memory contents comparison cannot be
+    assured to work. See: BUG#49482 and BUG#49481.
+  */
+  
+  if (table->file->ht->db_type == DB_TYPE_MYISAM)
+    goto record_compare_field_by_field;
+
   if (table->s->blob_fields + table->s->varchar_fields == 0)
   {
     result= cmp_record(table,record[1]);
@@ -8723,14 +8737,33 @@ static bool record_compare(TABLE *table)
     goto record_compare_exit;
   }
 
+record_compare_field_by_field:
+
   /* Compare updated fields */
   for (Field **ptr=table->field ; *ptr ; ptr++)
   {
-    if ((*ptr)->cmp_binary_offset(table->s->rec_buff_length))
+    Field *f= *ptr;
+
+    /* if just one of the fields is null then there is no match */
+    if ((f->is_null_in_record(table->record[0])) ==
+         !(f->is_null_in_record(table->record[1])))
     {
       result= TRUE;
       goto record_compare_exit;
     }
+
+    /* if both fields are not null then we can compare */
+    if (!(f->is_null_in_record(table->record[0])) &&
+        !(f->is_null_in_record(table->record[1])))
+    {
+      if (f->cmp_binary_offset(table->s->rec_buff_length))
+      {
+        result= TRUE;
+        goto record_compare_exit;
+      }
+    }
+
+    /* if both fields are null then there is a match. compare next field */
   }
 
 record_compare_exit:


Attachment: [text/bzr-bundle] bzr/luis.soares@sun.com-20091206045112-knstimnlla50bkfq.bundle
Thread
bzr commit into mysql-5.1-bugteam branch (luis.soares:3247) Bug#49481Luis Soares6 Dec
  • Re: bzr commit into mysql-5.1-bugteam branch (luis.soares:3247)Bug#49481Mats Kindahl11 Dec
    • Re: bzr commit into mysql-5.1-bugteam branch (luis.soares:3247)Bug#49481Luís Soares11 Dec
  • Re: bzr commit into mysql-5.1-bugteam branch (luis.soares:3247)Bug#49481Alfranio Correia29 Dec