diff options
Diffstat (limited to 'sql/sql_select.h')
| -rw-r--r-- | sql/sql_select.h | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/sql/sql_select.h b/sql/sql_select.h index c4f5dcba115..6732eb354d6 100644 --- a/sql/sql_select.h +++ b/sql/sql_select.h @@ -1,7 +1,7 @@ #ifndef SQL_SELECT_INCLUDED #define SQL_SELECT_INCLUDED -/* Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved. +/* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -160,6 +160,20 @@ typedef struct st_join_table { TABLE *table; KEYUSE *keyuse; /**< pointer to first used key */ SQL_SELECT *select; + /** + When doing filesort, the select object is used for building the + sort index. After the sort index is built, the pointer to the + select object is set to NULL to avoid that it is used when reading + the result records (@see create_sort_index()). For subqueries that + do filesort and that are executed multiple times, the pointer to + the select object must be restored before the next execution both + to ensure that the select object is used and to be able to cleanup + the select object after the final execution of the subquery. In + order to be able to restore the pointer to the select object, it + is saved in saved_select in create_sort_index() and restored in + JOIN::exec() after the main select is done. + */ + SQL_SELECT *saved_select; COND *select_cond; QUICK_SELECT_I *quick; Item **on_expr_ref; /**< pointer to the associated on expression */ |