MySQL Bugs: #60811: slow timezone functions

Bug #60811	slow timezone functions
Submitted:	8 Apr 2011 23:41	Modified:	10 Apr 2011 9:29
Reporter:	Steven Barre	Email Updates:
Status:	Verified	Impact on me:	None
Category:	MySQL Server: General	Severity:	S5 (Performance)
Version:	5.0.93, 5.5.12, 5.0.77-4.el5_5.4	OS:	Any (RHEL 5.5, Mac OS X)
Assigned to:		CPU Architecture:	Any

Description:
Functions involving timezones are much slower when using the SYSTEM time zone in MySQL as compared to any other time zone.

RPM mysql-server-5.0.77-4.el5_5.4
Kernel 2.6.18-194.17.4.el5

$cat /etc/sysconfig/clock

ZONE="US/Central"
UTC=false
ARC=false

mysql> SELECT @@global.time_zone, @@session.time_zone;                          +--------------------+---------------------+
| @@global.time_zone | @@session.time_zone |
+--------------------+---------------------+
| SYSTEM             | SYSTEM              |
+--------------------+---------------------+

How to repeat:
mysql> SET time_zone = 'US/Central'; SELECT BENCHMARK( 1000000, FROM_UNIXTIME( 1302301855));
Query OK, 0 rows affected (0.00 sec)

+-------------------------------------------------+
| BENCHMARK( 1000000, FROM_UNIXTIME( 1302301855)) |
+-------------------------------------------------+
|                                               0 |
+-------------------------------------------------+
1 row in set (0.57 sec)

mysql> SET time_zone = 'SYSTEM'; SELECT BENCHMARK( 1000000, FROM_UNIXTIME( 1302301855));
Query OK, 0 rows affected (0.00 sec)

+-------------------------------------------------+
| BENCHMARK( 1000000, FROM_UNIXTIME( 1302301855)) |
+-------------------------------------------------+
|                                               0 |
+-------------------------------------------------+
1 row in set (0.90 sec)

Suggested fix:
A workaround is to use default-time-zone in the cnf file to set a zone instead of using SYSTEM.

Verified with current 5.0.93 from bzr on Mac OS X:

macbook-pro:5.0 openxs$ bin/mysql -uroot test
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.0.93-debug Source distribution

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> SET time_zone = 'US/Central'; SELECT BENCHMARK( 1000000, FROM_UNIXTIME( 1302301855));
Query OK, 0 rows affected (0.01 sec)

+-------------------------------------------------+
| BENCHMARK( 1000000, FROM_UNIXTIME( 1302301855)) |
+-------------------------------------------------+
|                                               0 | 
+-------------------------------------------------+
1 row in set (1.13 sec)

mysql> SET time_zone = 'US/Central'; SELECT BENCHMARK( 1000000, FROM_UNIXTIME( 1302301855));
Query OK, 0 rows affected (0.00 sec)

+-------------------------------------------------+
| BENCHMARK( 1000000, FROM_UNIXTIME( 1302301855)) |
+-------------------------------------------------+
|                                               0 | 
+-------------------------------------------------+
1 row in set (1.13 sec)

mysql> SET time_zone = 'SYSTEM'; SELECT BENCHMARK( 1000000, FROM_UNIXTIME( 1302301855));
Query OK, 0 rows affected (0.00 sec)

+-------------------------------------------------+
| BENCHMARK( 1000000, FROM_UNIXTIME( 1302301855)) |
+-------------------------------------------------+
|                                               0 | 
+-------------------------------------------------+
1 row in set (1.48 sec)

mysql> SET time_zone = 'SYSTEM'; SELECT BENCHMARK( 1000000, FROM_UNIXTIME( 1302301855));
Query OK, 0 rows affected (0.00 sec)

+-------------------------------------------------+
| BENCHMARK( 1000000, FROM_UNIXTIME( 1302301855)) |
+-------------------------------------------------+
|                                               0 | 
+-------------------------------------------------+
1 row in set (1.45 sec)

MySQL 5.5 is also affected:

macbook-pro:5.5 openxs$ bin/mysql -uroot testReading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.5.12-debug Source distribution

Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> SET time_zone = 'US/Central'; SELECT BENCHMARK( 1000000, FROM_UNIXTIME( 1302301855));
Query OK, 0 rows affected (0.03 sec)

+-------------------------------------------------+
| BENCHMARK( 1000000, FROM_UNIXTIME( 1302301855)) |
+-------------------------------------------------+
|                                               0 |
+-------------------------------------------------+
1 row in set (1.12 sec)

mysql> SET time_zone = 'US/Central'; SELECT BENCHMARK( 1000000, FROM_UNIXTIME( 1302301855));
Query OK, 0 rows affected (0.00 sec)

+-------------------------------------------------+
| BENCHMARK( 1000000, FROM_UNIXTIME( 1302301855)) |
+-------------------------------------------------+
|                                               0 |
+-------------------------------------------------+
1 row in set (1.11 sec)

mysql> SET time_zone = 'SYSTEM'; SELECT BENCHMARK( 1000000, FROM_UNIXTIME( 1302301855));
Query OK, 0 rows affected (0.01 sec)

+-------------------------------------------------+
| BENCHMARK( 1000000, FROM_UNIXTIME( 1302301855)) |
+-------------------------------------------------+
|                                               0 |
+-------------------------------------------------+
1 row in set (1.43 sec)

mysql> SET time_zone = 'SYSTEM'; SELECT BENCHMARK( 1000000, FROM_UNIXTIME( 1302301855));
Query OK, 0 rows affected (0.00 sec)

+-------------------------------------------------+
| BENCHMARK( 1000000, FROM_UNIXTIME( 1302301855)) |
+-------------------------------------------------+
|                                               0 |
+-------------------------------------------------+
1 row in set (1.47 sec)

Looks like this bug also affects selects from table by timestamp column

mysql> SET time_zone = 'UTC';

mysql> select count(*) from `tablename` where `date` < '2020-08-15 00:00:00';
1 row in set (0.12 sec)

mysql> SET time_zone = 'SYSTEM';

mysql> select count(*) from `tablename` where `date` < '2020-08-15 00:00:00';
1 row in set (0.33 sec)