diff options
Diffstat (limited to 'sql/sql_base.cc')
| -rw-r--r-- | sql/sql_base.cc | 25 |
1 files changed, 23 insertions, 2 deletions
diff --git a/sql/sql_base.cc b/sql/sql_base.cc index 4affca4434d..13d3af1b8d1 100644 --- a/sql/sql_base.cc +++ b/sql/sql_base.cc @@ -1,4 +1,4 @@ -/* Copyright (C) 2000-2006 MySQL AB +/* Copyright 2000-2008 MySQL AB, 2008 Sun Microsystems, Inc. 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 @@ -1111,6 +1111,27 @@ static void mark_temp_tables_as_free_for_reuse(THD *thd) */ if (table->child_l || table->parent) detach_merge_children(table, TRUE); + /* + Reset temporary table lock type to it's default value (TL_WRITE). + + Statements such as INSERT INTO .. SELECT FROM tmp, CREATE TABLE + .. SELECT FROM tmp and UPDATE may under some circumstances modify + the lock type of the tables participating in the statement. This + isn't a problem for non-temporary tables since their lock type is + reset at every open, but the same does not occur for temporary + tables for historical reasons. + + Furthermore, the lock type of temporary tables is not really that + important because they can only be used by one query at a time and + not even twice in a query -- a temporary table is represented by + only one TABLE object. Nonetheless, it's safer from a maintenance + point of view to reset the lock type of this singleton TABLE object + as to not cause problems when the table is reused. + + Even under LOCK TABLES mode its okay to reset the lock type as + LOCK TABLES is allowed (but ignored) for a temporary table. + */ + table->reginfo.lock_type= TL_WRITE; } } } @@ -4699,7 +4720,7 @@ int open_tables(THD *thd, TABLE_LIST **start, uint *counter, uint flags) else if (tables->lock_type == TL_READ_DEFAULT) tables->table->reginfo.lock_type= read_lock_type_for_table(thd, tables->table); - else if (tables->table->s->tmp_table == NO_TMP_TABLE) + else tables->table->reginfo.lock_type= tables->lock_type; } tables->table->grant= tables->grant; |