[MDEV-11361] Equal condition propagation does not work for DECIMAL and temporal dynamic SQL parameters Created: 2016-11-27  Updated: 2019-11-19

Status: Open
Project: MariaDB Server
Component/s: Data types, Prepared Statements
Affects Version/s: 10.0, 10.1, 10.2, 10.3, 10.4
Fix Version/s: 10.4

Type: Bug Priority: Major
Reporter: Alexander Barkov Assignee: Alexander Barkov
Resolution: Unresolved Votes: 0
Labels: None

Issue Links:
Relates
relates to MDEV-4912 Data type plugin API version 1 Closed
relates to MDEV-11362 True condition elimination does not w... Closed
relates to MDEV-16426 Optimizer erroneously treats equal co... Closed
Epic Link: Data type cleanups

 Description   

I am testing equal expression propagation for various data types:

INT

DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1),(2),(3),(4);
EXECUTE IMMEDIATE 'EXPLAIN EXTENDED SELECT * FROM t1 WHERE a+1=? AND a+1<=10' USING 10;
SHOW WARNINGS;

+-------+------+-----------------------------------------------------------------------------------+
| Level | Code | Message                                                                           |
+-------+------+-----------------------------------------------------------------------------------+
| Note  | 1003 | select `test`.`t1`.`a` AS `a` from `test`.`t1` where ((`test`.`t1`.`a` + 1) = 10) |
+-------+------+-----------------------------------------------------------------------------------+

Works fine, the condition was simplified.

DOUBLE

DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (a DOUBLE);
INSERT INTO t1 VALUES (1),(2),(3),(4);
EXECUTE IMMEDIATE 'EXPLAIN EXTENDED SELECT * FROM t1 WHERE a+1=? AND a+1<=10' USING 10e0;
SHOW WARNINGS;

+-------+------+-----------------------------------------------------------------------------------+
| Level | Code | Message                                                                           |
+-------+------+-----------------------------------------------------------------------------------+
| Note  | 1003 | select `test`.`t1`.`a` AS `a` from `test`.`t1` where ((`test`.`t1`.`a` + 1) = 10) |
+-------+------+-----------------------------------------------------------------------------------+

Works fine.

DATE

DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (a DATE);
INSERT INTO t1 VALUES (1),(2),(3),(4);
EXECUTE IMMEDIATE "EXPLAIN EXTENDED SELECT * FROM t1 WHERE COALESCE(a)=? AND COALESCE(a) <=DATE'2001-01-01'" USING DATE'2001-01-01';
SHOW WARNINGS;

+-------+------+-----------------------------------------------------------------------------------------------+
| Level | Code | Message                                                                                       |
+-------+------+-----------------------------------------------------------------------------------------------+
| Note  | 1003 | select `test`.`t1`.`a` AS `a` from `test`.`t1` where (coalesce(`test`.`t1`.`a`) = 2001-01-01) |
+-------+------+-----------------------------------------------------------------------------------------------+

Works fine.

DECIMAL

DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (a DECIMAL(10,2));
INSERT INTO t1 VALUES (1),(2),(3),(4);
EXECUTE IMMEDIATE 'EXPLAIN EXTENDED SELECT * FROM t1 WHERE a+1=? AND a+1<=10' USING 10.00;
SHOW WARNINGS;

+-------+------+--------------------------------------------------------------------------------------------------------------------------+
| Level | Code | Message                                                                                                                  |
+-------+------+--------------------------------------------------------------------------------------------------------------------------+
| Note  | 1003 | select `test`.`t1`.`a` AS `a` from `test`.`t1` where (((`test`.`t1`.`a` + 1) = 10.00) and ((`test`.`t1`.`a` + 1) <= 10)) |
+-------+------+--------------------------------------------------------------------------------------------------------------------------+

Propagation did not work, the condition was not simplified.

This happens because DECIMAL_VALIE is not handled in Item_param::clone_item.

Note, if I change the parameter to an explicit DECIMAL literal, it correctly propagates equal conditions:

DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (a DECIMAL(10,2));
INSERT INTO t1 VALUES (1),(2),(3),(4);
EXECUTE IMMEDIATE 'EXPLAIN EXTENDED SELECT * FROM t1 WHERE a+1=10.00 AND a+1<=10';
SHOW WARNINGS;

+-------+------+--------------------------------------------------------------------------------------+
| Level | Code | Message                                                                              |
+-------+------+--------------------------------------------------------------------------------------+
| Note  | 1003 | select `test`.`t1`.`a` AS `a` from `test`.`t1` where ((`test`.`t1`.`a` + 1) = 10.00) |
+-------+------+--------------------------------------------------------------------------------------+


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