Mysql – How to enable queries logs in MariaDB

loglogsmariadbMySQL

I'm running mysql Ver 15.1 Distrib 5.5.46-MariaDB in CentOS 6.7 server. I'm trying to get queries logged and I'm doing by redirecting log to files as shown below:

#/etc/my.cnf.d/server.cnf
# this is only for the mysqld standalone daemon
[mysqld]
#
# * Fine Tuning
#
key_buffer              = 16M
max_allowed_packet      = 512M
thread_stack            = 192K
thread_cache_size       = 8

log-output = FILE

#General Query Log
general_log
general_log_file        = /var/log/mysql/mysql_query.log

#Error Log
log_error               = /var/log/mysql/mysql_error.log

#Slow Query Log
log-slow-queries
slow_query_log          = 1
slow_query_log_file     = /var/log/mysql/mysql_slow.log
long_query_time         = 2
log-queries-not-using-indexes

collation-server = utf8_general_ci
init-connect='SET NAMES utf8'
character-set-server = utf8

Before restart MySQL service I did run the following command to create each file and assign proper permissions:

mkdir -p /var/log/mysql && touch /var/log/mysql/mysql_query.log && touch /var/log/mysql/mysql_error.log && touch /var/log/mysql/mysql_slow.log && chown -R mysql:mysql /var/log/mysql/

I have restarted the MySQL daemon:

service mysql restart

After restart the MySQL server I can see the files but with 0 size so MySQL is not sending anything to those files. I did run the following query on MySQL console SHOW VARIABLES LIKE '%log%' and below is the result and as you may notice changes are not made at server:

+-------------------------------------------+--------------------------------------------------------------------------------------------------------------+
| Variable_name                             | Value                                                                                                        |
+-------------------------------------------+--------------------------------------------------------------------------------------------------------------+
| aria_checkpoint_log_activity              | 1048576                                                                                                      |
| aria_log_file_size                        | 1073741824                                                                                                   |
| aria_log_purge_type                       | immediate                                                                                                    |
| aria_sync_log_dir                         | NEWFILE                                                                                                      |
| back_log                                  | 50                                                                                                           |
| binlog_annotate_row_events                | OFF                                                                                                          |
| binlog_cache_size                         | 32768                                                                                                        |
| binlog_checksum                           | NONE                                                                                                         |
| binlog_direct_non_transactional_updates   | OFF                                                                                                          |
| binlog_format                             | STATEMENT                                                                                                    |
| binlog_optimize_thread_scheduling         | ON                                                                                                           |
| binlog_stmt_cache_size                    | 32768                                                                                                        |
| expire_logs_days                          | 0                                                                                                            |
| general_log                               | OFF                                                                                                          |
| general_log_file                          | pdone-prod.log                                                                                               |
| innodb_flush_log_at_trx_commit            | 1                                                                                                            |
| innodb_locks_unsafe_for_binlog            | OFF                                                                                                          |
| innodb_log_block_size                     | 512                                                                                                          |
| innodb_log_buffer_size                    | 8388608                                                                                                      |
| innodb_log_file_size                      | 5242880                                                                                                      |
| innodb_log_files_in_group                 | 2                                                                                                            |
| innodb_log_group_home_dir                 | ./                                                                                                           |
| innodb_mirrored_log_groups                | 1                                                                                                            |
| innodb_recovery_update_relay_log          | OFF                                                                                                          |
| innodb_use_global_flush_log_at_trx_commit | ON                                                                                                           |
| log                                       | OFF                                                                                                          |
| log_bin                                   | OFF                                                                                                          |
| log_bin_trust_function_creators           | OFF                                                                                                          |
| log_error                                 | /var/lib/mysql/pdone-prod.pdi-inc.com.err                                                                    |
| log_output                                | FILE                                                                                                         |
| log_queries_not_using_indexes             | OFF                                                                                                          |
| log_slave_updates                         | OFF                                                                                                          |
| log_slow_filter                           | admin,filesort,filesort_on_disk,full_join,full_scan,query_cache,query_cache_miss,tmp_table,tmp_table_on_disk |
| log_slow_queries                          | OFF                                                                                                          |
| log_slow_rate_limit                       | 1                                                                                                            |
| log_slow_verbosity                        |                                                                                                              |
| log_warnings                              | 1                                                                                                            |
| max_binlog_cache_size                     | 18446744073709547520                                                                                         |
| max_binlog_size                           | 1073741824                                                                                                   |
| max_binlog_stmt_cache_size                | 18446744073709547520                                                                                         |
| max_relay_log_size                        | 0                                                                                                            |
| relay_log                                 |                                                                                                              |
| relay_log_index                           |                                                                                                              |
| relay_log_info_file                       | relay-log.info                                                                                               |
| relay_log_purge                           | ON                                                                                                           |
| relay_log_recovery                        | OFF                                                                                                          |
| relay_log_space_limit                     | 0                                                                                                            |
| slow_query_log                            | OFF                                                                                                          |
| slow_query_log_file                       | pdone-prod-slow.log                                                                                          |
| sql_log_bin                               | ON                                                                                                           |
| sql_log_off                               | OFF                                                                                                          |
| sync_binlog                               | 0                                                                                                            |
| sync_relay_log                            | 0                                                                                                            |
| sync_relay_log_info                       | 0                                                                                                            |
+-------------------------------------------+--------------------------------------------------------------------------------------------------------------+

What could be wrong here? Why logs are not being sent to those files?

UPDATES

@rick-james: I did check permissions by running:

# ls -ld /var/log/mysql/
drwxrwxrwx 2 mysql mysql 4096 Nov 30 16:44 /var/log/mysql/

And apparently are good (777).

@ypercube: Below is the result of the command you want me to run.

# ls -l /var/log/mysql/
total 0
-rw-r--r-- 1 mysql mysql 0 Nov 30 16:44 mysql_error.log
-rw-r--r-- 1 mysql mysql 0 Nov 30 16:44 mysql_query.log
-rw-r--r-- 1 mysql mysql 0 Nov 30 16:44 mysql_slow.log

In first place all files was chmod as 644 but I change that to be 775 now result looks like:

# ls -l /var/log/mysql/
total 0
-rwxrwxr-x 1 mysql mysql 0 Nov 30 16:44 mysql_error.log
-rwxrwxr-x 1 mysql mysql 0 Nov 30 16:44 mysql_query.log
-rwxrwxr-x 1 mysql mysql 0 Nov 30 16:44 mysql_slow.log

But not change at all, logs are not beeing saved in those files. Why?

Best Answer

Ok, finally I found where the issue was! For some reason I delete /etc/my.cnf file (perhaps when I uninstall MySQL or something else) and that's the file including everything under /etc/my.cnf.d because of that changes don't take effect. My bad. Thanks for your time

UPDATE 2013-04-15 18:04 EDT

I just noticed you have innodb_file_per_table OFF. What gives ?

You currently have all the InnoDB data and the corresponding index sitting in a single file.
Any CREATE TABLE statement must make data dictionary updates and look for space (small but annoying in this instance)
Internal Fragmentation of ibdata1
Dropping a table means scanning the table and its indexes for availability to lock. With data and index pages possibly fragmented, this takes spindles, seek time, and latency.
See Pictorial Representation of ibdata1 to see everything that goes into ibdata1

Recommendation : Remove all Data and Index Pages from ibdata1

This will give ibdata1 a breather to handle just data dictionary and MVCC management. In addition, ibdata1 will stay rather lean and mean and can be read more quickly.

You will need to perform the InnoDB Infrastructure Cleanup. I wrote out all the steps back on October 29, 2010 in StackOverflow.

UPDATE 2013-04-22 08:10 EDT

Three suggestions

SUGGESTION 1 : I just noticed something else. You are using an ancient version of MySQL (5.0.45). You should think about upgrading to MySQL 5.6.11 as it performs significantly faster that MySQL 5.5 and way faster than MySQL 5.0.

SUGGESTION 2 : You should also go ahead and implement the InnoDB Infrastructure Cleanup.

SUGGESTION 3 : You should also check the disk itself. If the data is sitting on a RAID10 set, one of the disks may have an issues. Check the disk controller's battery as well because it can slow down disk caching and affect read performance.

Mysql – How to debug a db memory-leak causing thesql to go before it’s own limits

...even surpassing it's theorically maximum possible allocation.

[OK] Maximum possible memory usage: 7.3G (46% of installed RAM)

There is not actually a way to calculate maximum possible memory usage for MySQL, because there is no cap on the memory it can request from the system.

The calculation done by mysqltuner.pl is only an estimate, based on a formula that doesn't take into account all possible variables, because if all possible variables were taken into account, the answer would always be "infinite." It's unfortunate that it's labeled this way.

Here is my theory on what's contributing to your excessive memory usage:

thread_cache_size       = 128

Given that your max_connections is set to 200, the value of 128 for thread_cache_size seems far too high. Here's what makes me think this might be contributing to your problem:

When a thread is no longer needed, the memory allocated to it is released and returned to the system unless the thread goes back into the thread cache. In that case, the memory remains allocated.

^{http://dev.mysql.com/doc/refman/5.6/en/memory-use.html}

If your workload causes even an occasional client thread to require a large amount of memory, those threads may be holding onto that memory, then going back to the pool and sitting around, continuing to hold on to memory they don't technically "need" any more, on the premise that holding on to the memory is less costly than releasing it if you're likely to need it again.

I think it's worth a try to do the following, after first making a note of how much memory MySQL is using at the moment.

Note how many threads are currently cached:

mysql> show status like 'Threads_cached';
+----------------+-------+
| Variable_name  | Value |
+----------------+-------+
| Threads_cached | 9     |
+----------------+-------+
1 row in set (0.00 sec)

Next, disable the thread cache.

mysql> SET GLOBAL thread_cache_size = 0;

This disables the thread cache, but the cached threads will stay in the pool until they're used one more time. Disconnect from the server, then reconnect and repeat.

mysql> show status like 'Threads_cached';

Continue disconnecting, reconnecting, and checking until the counter reaches 0.

Then, see how much memory MySQL is holding.

You may see a decrease, possibly significant, and then again you may not. I tested this on one of my systems, which had 9 threads in the cache. Once those threads had all been cleared out of the cache, the total memory held by MySQL did decrease... not by much, but it does illustrate that threads in the cache do release at least some memory when they are destroyed.

If you see a significant decrease, you may have found your problem. If you don't, then there's one more thing that needs to happen, and how quickly it can happen depends on your environment.

If the theory holds that the other threads -- the ones currently servicing active client connections -- have significant memory allocated to them, either because of recent work in their current client session or because of work requiring a lot of memory that was done by another connection prior to them languishing in the pool, then you won't see all of the potential reduction in memory consumption until those threads are allowed to die and be destroyed. Presumably your application doesn't hold them forever, but how long it will take to know for sure whether there's a difference will depend on whether you have the option of cycling your application (dropping and reconnecting the client threads) or if you'll have to just wait for them to be dropped and reconnected over time on their own.

But... it seems like a worthwhile test. You should not see a substantial performance penalty by setting thread_cache_size to 0. Fortunately, thread_cache_size is a dynamic variable, so you can freely change it with the server running.

Best Answer

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MySQL database drop insanely slow

UPDATE 2013-04-15 18:04 EDT

Recommendation : Remove all Data and Index Pages from ibdata1

UPDATE 2013-04-22 08:10 EDT

Mysql – How to debug a db memory-leak causing thesql to go before it’s own limits

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