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.

1 files changed, 6 insertions, 2 deletions

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;