From f8bf2a0170b385bbba8f9f8dc97841f58229d39a Mon Sep 17 00:00:00 2001 From: Dmitry Shulga Date: Mon, 12 Apr 2021 19:28:10 +0700 Subject: MDEV-25108: Running of the EXPLAIN EXTENDED statement produces extra warning in case it is executed in PS (prepared statement) mode The EXPLAIN EXTENDED statement run as a prepared statement can produce extra warning comparing with a case when EXPLAIN EXTENDED statement is run as a regular statement. For example, the following test case CREATE TABLE t1 (c int); CREATE TABLE t2 (d int); EXPLAIN EXTENDED SELECT (SELECT 1 FROM t2 WHERE d = c) FROM t1; produces the extra warning "Field or reference 'c' of SELECT #2 was resolved in SELECT #1" in case the above mentioned "EXPLAIN EXTENDED" statement is executed in PS mode, that is by submitting the following statements: PREPARE stmt FROM "EXPLAIN EXTENDED SELECT (SELECT 1 FROM t2 WHERE d = c) FROM t1"; EXECUTE stmt; The reason of the extra warning emittion is in a way items are handled (being fixed) during execution of the JOIN::prepare() method. The method Item_field::fix_fields() calls the find_field_in_tables() function in case a field hasn't been associated yet with the item. Implementation of the find_field_in_tables() function first checks whether a table containing the required field was already opened and cached. It is done by checking the data member item->cached_table. This data member is set on handling the PRERARE FROM statement and checked on executing the EXECUTE statement. If the data member item->cached_table is set the find_field_in_tables() function invoked and the mark_select_range_as_dependent() function called if the field is an outer referencee. The mark_select_range_as_dependent() function calls the mark_as_dependent() function that finally invokes the push_warning_printf() function that produces extra warning. To fix the issue, calling of push_warning_printf() is elimited in case it was run indirectly in result of hanlding already opened table from the Item_field::fix_fields() method. --- sql/item.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'sql/item.h') diff --git a/sql/item.h b/sql/item.h index cb1e8519b27..b13336939f9 100644 --- a/sql/item.h +++ b/sql/item.h @@ -6088,7 +6088,8 @@ void mark_select_range_as_dependent(THD *thd, st_select_lex *last_select, st_select_lex *current_sel, Field *found_field, Item *found_item, - Item_ident *resolved_item); + Item_ident *resolved_item, + bool suppress_warning_output); extern Cached_item *new_Cached_item(THD *thd, Item *item, bool pass_through_ref); -- cgit v1.2.1