Fix for bug#51304: checksum table gives different results

for same data when using bit fields

Problem: checksum for BIT fields may be computed incorrectly 
in some cases due to its storage peculiarity.

Fix: convert a BIT field to a string then calculate its checksum.

mysql-test/r/myisam.result

@@ -2339,4 +2339,21 @@ CHECK TABLE t1;
 Table	Op	Msg_type	Msg_text
 test.t1	check	status	OK
 DROP TABLE t1;
+#
+# Bug#51304: checksum table gives different results
+# for same data when using bit fields
+#
+CREATE TABLE t1(a INT, b BIT(1));
+INSERT INTO t1 VALUES(1, 0), (2, 1);
+CREATE TABLE t2 SELECT * FROM t1;
+CHECKSUM TABLE t1 EXTENDED;
+Table	Checksum
+test.t1	3775188275
+CHECKSUM TABLE t2 EXTENDED;
+Table	Checksum
+test.t2	3775188275
+CHECKSUM TABLE t3 EXTENDED;
+Table	Checksum
+test.t3	3775188275
+DROP TABLE t1, t2, t3;
 End of 5.1 tests

mysql-test/t/myisam.test

@@ -1587,5 +1587,20 @@ REPLACE INTO t1 VALUES
 CHECK TABLE t1;
 DROP TABLE t1;
 
---echo End of 5.1 tests
 
+--echo #
+--echo # Bug#51304: checksum table gives different results
+--echo # for same data when using bit fields
+--echo #
+CREATE TABLE t1(a INT, b BIT(1));
+INSERT INTO t1 VALUES(1, 0), (2, 1);
+CREATE TABLE t2 SELECT * FROM t1;
+--copy_file $MYSQLD_DATADIR/test/t1.frm $MYSQLD_DATADIR/test/t3.frm
+--copy_file $MYSQLD_DATADIR/test/t1.MYD $MYSQLD_DATADIR/test/t3.MYD
+--copy_file $MYSQLD_DATADIR/test/t1.MYI $MYSQLD_DATADIR/test/t3.MYI
+CHECKSUM TABLE t1 EXTENDED;
+CHECKSUM TABLE t2 EXTENDED;
+CHECKSUM TABLE t3 EXTENDED;
+DROP TABLE t1, t2, t3;
+
+--echo End of 5.1 tests

sql/sql_table.cc

@@ -7934,22 +7934,28 @@ bool mysql_checksum_table(THD *thd, TABLE_LIST *tables,
 	    for (uint i= 0; i < t->s->fields; i++ )
 	    {
 	      Field *f= t->field[i];
-        enum_field_types field_type= f->type();
-        /*
-          BLOB and VARCHAR have pointers in their field, we must convert
-          to string; GEOMETRY is implemented on top of BLOB.
-        */
-        if ((field_type == MYSQL_TYPE_BLOB) ||
-            (field_type == MYSQL_TYPE_VARCHAR) ||
-            (field_type == MYSQL_TYPE_GEOMETRY))
-	      {
-		String tmp;
-		f->val_str(&tmp);
-		row_crc= my_checksum(row_crc, (uchar*) tmp.ptr(), tmp.length());
+
+             /*
+               BLOB and VARCHAR have pointers in their field, we must convert
+               to string; GEOMETRY is implemented on top of BLOB.
+               BIT may store its data among NULL bits, convert as well.
+             */
+              switch (f->type()) {
+                case MYSQL_TYPE_BLOB:
+                case MYSQL_TYPE_VARCHAR:
+                case MYSQL_TYPE_GEOMETRY:
+                case MYSQL_TYPE_BIT:
+                {
+                  String tmp;
+                  f->val_str(&tmp);
+                  row_crc= my_checksum(row_crc, (uchar*) tmp.ptr(),
+                           tmp.length());
+                  break;
+                }
+                default:
+                  row_crc= my_checksum(row_crc, f->ptr, f->pack_length());
+                  break;
 	      }
-	      else
-		row_crc= my_checksum(row_crc, f->ptr,
-				     f->pack_length());
 	    }
 
 	    crc+= row_crc;