diff options
Diffstat (limited to 'sql/sql_update.cc')
| -rw-r--r-- | sql/sql_update.cc | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/sql/sql_update.cc b/sql/sql_update.cc index 19df0661db3..f79a9669a50 100644 --- a/sql/sql_update.cc +++ b/sql/sql_update.cc @@ -544,6 +544,26 @@ int multi_update::prepare(List<Item> ¬_used_values) for (i=0 ; i < table_count ; i++) set_if_bigger(max_fields, fields_for_table[i]->elements); copy_field= new Copy_field[max_fields]; + + /* + Mark all copies of tables that are updates to ensure that + init_read_record() will not try to enable a cache on them + + The problem is that for queries like + + UPDATE t1, t1 AS t2 SET t1.b=t2.c WHERE t1.a=t2.a; + + the row buffer may contain things that doesn't match what is on disk + which will cause an error when reading a row. + (This issue is mostly relevent for MyISAM tables) + */ + for (table_ref= all_tables; table_ref; table_ref=table_ref->next) + { + TABLE *table=table_ref->table; + if (!(tables_to_update & table->map) && + check_dup(table_ref->db, table_ref->real_name, update_tables)) + table->no_cache= 1; // Disable row cache + } DBUG_RETURN(thd->fatal_error != 0); } @@ -685,7 +705,7 @@ multi_update::~multi_update() { TABLE_LIST *table; for (table= update_tables ; table; table= table->next) - table->table->no_keyread=0; + table->table->no_keyread= table->table->no_cache= 0; if (tmp_tables) { |