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  1. MariaDB Server
  2. MDEV-8741

Equal field propagation leaves some remainders after simplifying WHERE zerofill_column=2010 AND zerofill_column>=2010

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          Description

          This script:

          DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (a INT ZEROFILL);
INSERT INTO t1 VALUES (2010),(2020);
EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=2010 AND a>=2010;
SHOW WARNINGS;

          returns

          +-------+------+---------------------------------------------------------------------------------------+
| Level | Code | Message                                                                               |
+-------+------+---------------------------------------------------------------------------------------+
| Note  | 1003 | select `test`.`t1`.`a` AS `a` from `test`.`t1` where ((`test`.`t1`.`a` = 2010) and 1) |
+-------+------+---------------------------------------------------------------------------------------+

          Notice, the a>=2010 part was simplified to constant, but the constant was not removed.

          The same problems is repeatable with the YEAR data type:

          DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (a YEAR);
INSERT INTO t1 VALUES (2010),(2020);
EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=2010 AND a>=2010;
SHOW WARNINGS;

          If I use "INT" instead of "INT ZEROFILL" or "YEAR", it works as expected:

          DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (2010),(2020);
EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=2010 AND a>=2010;
SHOW WARNINGS;

          returns:

          +-------+------+-------------------------------------------------------------------------------+
| Level | Code | Message                                                                       |
+-------+------+-------------------------------------------------------------------------------+
| Note  | 1003 | select `test`.`t1`.`a` AS `a` from `test`.`t1` where (`test`.`t1`.`a` = 2010) |
+-------+------+-------------------------------------------------------------------------------+

          as expected.

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                Bug - A problem which impairs or prevents the functions of the product. MDEV-8728 Fix a number of problems in equal field and equal expression propagation

                • Critical - Crashes, loss of data, severe memory leak.
                • Closed

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                  bar Alexander Barkov added a comment -

                  MySQL-5.7.8 does not seem to remove the constant part (the result of propagation) from the WHERE condition:

                  DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (a INT ZEROFILL);
INSERT INTO t1 VALUES (2010),(2020);
EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=2010 AND a>=2010;
SHOW WARNINGS;

                  returns

                  +---------+------+-------------------------------------------------------------------------------------------------------------------+
| Level   | Code | Message                                                                                                           |
+---------+------+-------------------------------------------------------------------------------------------------------------------+
| Warning | 1681 | 'EXTENDED' is deprecated and will be removed in a future release.                                                 |
| Note    | 1003 | /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where ((`test`.`t1`.`a` = 2010) and (2010 >= 2010)) |
+---------+------+-------------------------------------------------------------------------------------------------------------------
                  Show
                  bar Alexander Barkov added a comment - MySQL-5.7.8 does not seem to remove the constant part (the result of propagation) from the WHERE condition: DROP TABLE IF EXISTS t1; CREATE TABLE t1 (a INT ZEROFILL); INSERT INTO t1 VALUES (2010),(2020); EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=2010 AND a>=2010; SHOW WARNINGS; returns +---------+------+-------------------------------------------------------------------------------------------------------------------+ | Level | Code | Message | +---------+------+-------------------------------------------------------------------------------------------------------------------+ | Warning | 1681 | 'EXTENDED' is deprecated and will be removed in a future release. | | Note | 1003 | /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where ((`test`.`t1`.`a` = 2010) and (2010 >= 2010)) | +---------+------+-------------------------------------------------------------------------------------------------------------------

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                    • Assignee:
                      bar Alexander Barkov
                      Reporter:
                      bar Alexander Barkov
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                      • Created:
                        Updated:
                        Resolved: