Fix for bug #54007: assert in ha_myisam::index_next, HANDLER

Problem: the server missed the fact that one can read from 
2 indexes alternately using HANDLER interface.

Fix: check if the same (initialized) index is involved
reading next/prev values from the index.


mysql-test/r/handler_myisam.result:
  Fix for bug #54007: assert in ha_myisam::index_next, HANDLER
    - test result.
mysql-test/t/handler_myisam.test:
  Fix for bug #54007: assert in ha_myisam::index_next, HANDLER
    - test case.
sql/sql_handler.cc:
  Fix for bug #54007: assert in ha_myisam::index_next, HANDLER
    - check if we use the same (initialized) index 
  to read next/prev values from the index.

mysql-test/r/handler_myisam.result

@@ -769,4 +769,97 @@ a
 1
 HANDLER t1 CLOSE;
 DROP TABLE t1;
+#
+# Bug #54007: assert in ha_myisam::index_next , HANDLER
+#
+CREATE TABLE t1(a INT, b INT, PRIMARY KEY(a), KEY b(b), KEY ab(a, b));
+HANDLER t1 OPEN;
+HANDLER t1 READ FIRST;
+a	b
+HANDLER t1 READ `PRIMARY` NEXT;
+a	b
+HANDLER t1 READ ab NEXT;
+a	b
+HANDLER t1 READ b NEXT;
+a	b
+HANDLER t1 READ NEXT;
+a	b
+HANDLER t1 CLOSE;
+INSERT INTO t1 VALUES (2, 20), (1, 10), (4, 40), (3, 30);
+HANDLER t1 OPEN;
+HANDLER t1 READ FIRST;
+a	b
+2	20
+HANDLER t1 READ NEXT;
+a	b
+1	10
+HANDLER t1 READ `PRIMARY` NEXT;
+a	b
+1	10
+HANDLER t1 READ `PRIMARY` NEXT;
+a	b
+2	20
+HANDLER t1 READ ab NEXT;
+a	b
+1	10
+HANDLER t1 READ ab NEXT;
+a	b
+2	20
+HANDLER t1 READ b NEXT;
+a	b
+1	10
+HANDLER t1 READ b NEXT;
+a	b
+2	20
+HANDLER t1 READ b NEXT;
+a	b
+3	30
+HANDLER t1 READ b NEXT;
+a	b
+4	40
+HANDLER t1 READ b NEXT;
+a	b
+HANDLER t1 READ NEXT;
+a	b
+4	40
+HANDLER t1 READ NEXT;
+a	b
+3	30
+HANDLER t1 READ NEXT;
+a	b
+HANDLER t1 CLOSE;
+HANDLER t1 OPEN;
+HANDLER t1 READ FIRST;
+a	b
+2	20
+HANDLER t1 READ `PRIMARY` PREV;
+a	b
+4	40
+HANDLER t1 READ `PRIMARY` PREV;
+a	b
+3	30
+HANDLER t1 READ b PREV;
+a	b
+4	40
+HANDLER t1 READ b PREV;
+a	b
+3	30
+HANDLER t1 CLOSE;
+HANDLER t1 OPEN;
+HANDLER t1 READ FIRST;
+a	b
+2	20
+HANDLER t1 READ `PRIMARY` PREV LIMIT 3;
+a	b
+4	40
+3	30
+2	20
+HANDLER t1 READ b NEXT LIMIT 5;
+a	b
+1	10
+2	20
+3	30
+4	40
+HANDLER t1 CLOSE;
+DROP TABLE t1;
 End of 5.1 tests

mysql-test/t/handler_myisam.test

@@ -48,4 +48,53 @@ HANDLER t1 READ a NEXT;
 HANDLER t1 CLOSE;
 DROP TABLE t1;
 
+
+--echo #
+--echo # Bug #54007: assert in ha_myisam::index_next , HANDLER
+--echo #
+CREATE TABLE t1(a INT, b INT, PRIMARY KEY(a), KEY b(b), KEY ab(a, b));
+
+HANDLER t1 OPEN;
+HANDLER t1 READ FIRST;
+HANDLER t1 READ `PRIMARY` NEXT;
+HANDLER t1 READ ab NEXT;
+HANDLER t1 READ b NEXT;
+HANDLER t1 READ NEXT;
+HANDLER t1 CLOSE;
+
+INSERT INTO t1 VALUES (2, 20), (1, 10), (4, 40), (3, 30);
+HANDLER t1 OPEN;
+HANDLER t1 READ FIRST;
+HANDLER t1 READ NEXT;
+HANDLER t1 READ `PRIMARY` NEXT;
+HANDLER t1 READ `PRIMARY` NEXT;
+HANDLER t1 READ ab NEXT;
+HANDLER t1 READ ab NEXT;
+HANDLER t1 READ b NEXT;
+HANDLER t1 READ b NEXT;
+HANDLER t1 READ b NEXT;
+HANDLER t1 READ b NEXT;
+HANDLER t1 READ b NEXT;
+HANDLER t1 READ NEXT;
+HANDLER t1 READ NEXT;
+HANDLER t1 READ NEXT;
+HANDLER t1 CLOSE;
+
+HANDLER t1 OPEN;
+HANDLER t1 READ FIRST;
+HANDLER t1 READ `PRIMARY` PREV;
+HANDLER t1 READ `PRIMARY` PREV;
+HANDLER t1 READ b PREV;
+HANDLER t1 READ b PREV;
+HANDLER t1 CLOSE;
+
+HANDLER t1 OPEN;
+HANDLER t1 READ FIRST;
+HANDLER t1 READ `PRIMARY` PREV LIMIT 3;
+HANDLER t1 READ b NEXT LIMIT 5;
+HANDLER t1 CLOSE;
+
+DROP TABLE t1;
+
+
 --echo End of 5.1 tests

sql/sql_handler.cc

@@ -539,6 +539,14 @@ bool mysql_ha_read(THD *thd, TABLE_LIST *tables,
       my_error(ER_KEY_DOES_NOT_EXITS, MYF(0), keyname, tables->alias);
       goto err;
     }
+    /* Check if the same index involved. */
+    if ((uint) keyno != table->file->get_index())
+    {
+      if (mode == RNEXT)
+        mode= RFIRST;
+      else if (mode == RPREV)
+        mode= RLAST;
+    }
   }
 
   if (insert_fields(thd, &thd->lex->select_lex.context,
@@ -561,9 +569,16 @@ bool mysql_ha_read(THD *thd, TABLE_LIST *tables,
     case RNEXT:
       if (table->file->inited != handler::NONE)
       {
-        error=keyname ?
-	  table->file->index_next(table->record[0]) :
-	  table->file->rnd_next(table->record[0]);
+        if (keyname)
+        {
+          /* Check if we read from the same index. */
+          DBUG_ASSERT((uint) keyno == table->file->get_index());
+          error= table->file->index_next(table->record[0]);
+        }
+        else
+        {
+          error= table->file->rnd_next(table->record[0]);
+        }
         break;
       }
       /* else fall through */
@@ -584,6 +599,8 @@ bool mysql_ha_read(THD *thd, TABLE_LIST *tables,
       break;
     case RPREV:
       DBUG_ASSERT(keyname != 0);
+      /* Check if we read from the same index. */
+      DBUG_ASSERT((uint) keyno == table->file->get_index());
       if (table->file->inited != handler::NONE)
       {
         error=table->file->index_prev(table->record[0]);