Description:
MySQL manual (https://dev.mysql.com/doc/refman/5.7/en/ddl-log.html) eplains what is the DDL log, where and when it is created.
But it does not explain how large it can be and for how long time it exists.
In reality is may grow (indefinitely?) until server restarts. After successful startup it seems to disappear.
How to repeat:
Do some SQL that forces creation of ddl_log.log, like this:
mysql> alter table trange drop partition p1;
Query OK, 0 rows affected (1 min 21.54 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> alter table trange drop partition pmax;
Query OK, 0 rows affected (0.39 sec)
Records: 0 Duplicates: 0 Warnings: 0
for some non-empty partiitoned table:
mysql> show create table trange\G
*************************** 1. row ***************************
Table: trange
Create Table: CREATE TABLE `trange` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`c1` int(11) DEFAULT NULL,
`c2` int(11) DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `c1` (`c1`),
KEY `c2` (`c2`)
) ENGINE=InnoDB AUTO_INCREMENT=402 DEFAULT CHARSET=latin1 STATS_PERSISTENT=0
/*!50100 PARTITION BY RANGE (id)
(PARTITION p1 VALUES LESS THAN (100) ENGINE = InnoDB,
PARTITION p2 VALUES LESS THAN (200) ENGINE = InnoDB,
PARTITION p3 VALUES LESS THAN (300) ENGINE = InnoDB,
PARTITION pmax VALUES LESS THAN MAXVALUE ENGINE = InnoDB) */
1 row in set (0.00 sec)
mysql> start transaction;
Query OK, 0 rows affected (0.00 sec)
mysql> insert into trange(c1, c2) select c1, c2 from trange;
Query OK, 4 rows affected (0.02 sec)
Records: 4 Duplicates: 0 Warnings: 0
mysql> insert into trange(c1, c2) select c1, c2 from trange;
Query OK, 8 rows affected (0.00 sec)
Records: 8 Duplicates: 0 Warnings: 0
mysql> insert into trange(c1, c2) select c1, c2 from trange;
Query OK, 16 rows affected (0.00 sec)
Records: 16 Duplicates: 0 Warnings: 0
mysql> insert into trange(c1, c2) select c1, c2 from trange;
Query OK, 32 rows affected (0.00 sec)
Records: 32 Duplicates: 0 Warnings: 0
mysql> insert into trange(c1, c2) select c1, c2 from trange;
Query OK, 64 rows affected (0.00 sec)
Records: 64 Duplicates: 0 Warnings: 0
...
You will see the file is created in the datadir:
[openxs@fc23 5.7]$ ls -l data | grep ddl_log
-rw-r-----. 1 openxs openxs 20480 Nov 7 12:06 ddl_log.log
[openxs@fc23 5.7]$ lsof -p `pidof mysqld` | grep ddl
mysqld 2571 openxs 50u REG 8,3 20480 3163338 /home/openxs/dbs/5.7/data/ddl_log.log
Even though ALTER completes and there are no other transactions, even after clean shutdown this file remains:
[openxs@fc23 5.7]$ bin/mysqladmin -uroot shutdown
[openxs@fc23 5.7]$ ls -l data | grep ddl_log
-rw-r-----. 1 openxs openxs 20480 Nov 7 12:06 ddl_log.log
[openxs@fc23 5.7]$ ps aux | grep mysqld
openxs 3183 0.0 0.0 118488 2384 pts/2 S+ 12:10 0:00 grep --color=auto mysqld
But it disappears upon startup:
[openxs@fc23 5.7]$ bin/mysqld_safe --no-defaults &
[1] 3184
[openxs@fc23 5.7]$ 2016-11-07T10:11:37.257789Z mysqld_safe Logging to '/home/openxs/dbs/5.7/data/fc23.err'.
2016-11-07T10:11:37.287489Z mysqld_safe Starting mysqld daemon with databases from /home/openxs/dbs/5.7/data
[openxs@fc23 5.7]$ ls -l data | grep ddl_log
Suggested fix:
Please, explain more details about the ddl_log.log file in the manual, including those on when it disappears and how large it can be.
See the test case explained above and Bug #83708 for some hints.
