From c5c64a30d44f720ff3c9a6bfcdbf11a0bcc70797 Mon Sep 17 00:00:00 2001
From: Sergey Glukhov <Sergey.Glukhov@sun.com>
Date: Tue, 9 Dec 2008 16:59:47 +0400
Subject: [PATCH] Bug#31399 Wrong query result when doing join buffering over
 BIT fields if table has bit fields then uneven bits(if exist) are stored into
 null bits place. So we need to copy null bits in case of uneven bit field
 presence.

---
 mysql-test/r/type_bit.result | 26 ++++++++++++++++++++++++++
 mysql-test/t/type_bit.test   | 30 ++++++++++++++++++++++++++++++
 sql/sql_select.cc            |  8 ++++++--
 3 files changed, 62 insertions(+), 2 deletions(-)

diff --git a/mysql-test/r/type_bit.result b/mysql-test/r/type_bit.result
index 2a83d9b4c62..63dec0297d0 100644
--- a/mysql-test/r/type_bit.result
+++ b/mysql-test/r/type_bit.result
@@ -723,4 +723,30 @@ CREATE TABLE IF NOT EXISTS t1 (
 f1 bit(2) NOT NULL default b''
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_general_ci;
 ERROR 42000: Invalid default value for 'f1'
+create table t1bit7 (a1 bit(7) not null) engine=MyISAM;
+create table t2bit7 (b1 bit(7)) engine=MyISAM;
+insert into t1bit7 values (b'1100000');
+insert into t1bit7 values (b'1100001');
+insert into t1bit7 values (b'1100010');
+insert into t2bit7 values (b'1100001');
+insert into t2bit7 values (b'1100010');
+insert into t2bit7 values (b'1100110');
+select bin(a1) from t1bit7, t2bit7 where t1bit7.a1=t2bit7.b1;
+bin(a1)
+1100001
+1100010
+drop table t1bit7, t2bit7;
+create table t1bit7 (a1 bit(15) not null) engine=MyISAM;
+create table t2bit7 (b1 bit(15)) engine=MyISAM;
+insert into t1bit7 values (b'110000011111111');
+insert into t1bit7 values (b'110000111111111');
+insert into t1bit7 values (b'110001011111111');
+insert into t2bit7 values (b'110000111111111');
+insert into t2bit7 values (b'110001011111111');
+insert into t2bit7 values (b'110011011111111');
+select bin(a1) from t1bit7, t2bit7 where t1bit7.a1=t2bit7.b1;
+bin(a1)
+110000111111111
+110001011111111
+drop table t1bit7, t2bit7;
 End of 5.0 tests
diff --git a/mysql-test/t/type_bit.test b/mysql-test/t/type_bit.test
index 81dca17f112..bdc678688f1 100644
--- a/mysql-test/t/type_bit.test
+++ b/mysql-test/t/type_bit.test
@@ -367,4 +367,34 @@ CREATE TABLE IF NOT EXISTS t1 (
 f1 bit(2) NOT NULL default b''
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_general_ci;
 
+
+#
+# Bug#31399 Wrong query result when doing join buffering over BIT fields 
+#
+create table t1bit7 (a1 bit(7) not null) engine=MyISAM; 
+create table t2bit7 (b1 bit(7)) engine=MyISAM; 
+
+insert into t1bit7 values (b'1100000'); 
+insert into t1bit7 values (b'1100001'); 
+insert into t1bit7 values (b'1100010'); 
+insert into t2bit7 values (b'1100001'); 
+insert into t2bit7 values (b'1100010'); 
+insert into t2bit7 values (b'1100110'); 
+
+select bin(a1) from t1bit7, t2bit7 where t1bit7.a1=t2bit7.b1; 
+drop table t1bit7, t2bit7; 
+
+create table t1bit7 (a1 bit(15) not null) engine=MyISAM; 
+create table t2bit7 (b1 bit(15)) engine=MyISAM; 
+
+insert into t1bit7 values (b'110000011111111'); 
+insert into t1bit7 values (b'110000111111111'); 
+insert into t1bit7 values (b'110001011111111'); 
+insert into t2bit7 values (b'110000111111111'); 
+insert into t2bit7 values (b'110001011111111'); 
+insert into t2bit7 values (b'110011011111111'); 
+
+select bin(a1) from t1bit7, t2bit7 where t1bit7.a1=t2bit7.b1; 
+drop table t1bit7, t2bit7; 
+
 --echo End of 5.0 tests
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 2ac33c4e07f..b080fff8725 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -13233,6 +13233,7 @@ join_init_cache(THD *thd,JOIN_TAB *tables,uint table_count)
   length=0;
   for (i=0 ; i < table_count ; i++)
   {
+    bool have_bit_fields= FALSE;
     uint null_fields=0,used_fields;
 
     Field **f_ptr,*field;
@@ -13247,13 +13248,16 @@ join_init_cache(THD *thd,JOIN_TAB *tables,uint table_count)
 	length+=field->fill_cache_field(copy);
 	if (copy->blob_field)
 	  (*blob_ptr++)=copy;
-	if (field->maybe_null())
+	if (field->real_maybe_null())
 	  null_fields++;
+        if (field->type() == MYSQL_TYPE_BIT &&
+            ((Field_bit*)field)->bit_len)
+          have_bit_fields= TRUE;    
 	copy++;
       }
     }
     /* Copy null bits from table */
-    if (null_fields && tables[i].table->s->null_fields)
+    if (null_fields || have_bit_fields)
     {						/* must copy null bits */
       copy->str=(char*) tables[i].table->null_flags;
       copy->length= tables[i].table->s->null_bytes;