Where can I find the mysql slow log?

Question

Just as the title says, where can I see it ?

Are there any config options for it ( like how many ms would determine if a query is slow or not ) ?

score 31 · Answer 1 · edited Sep 28 '11 at 20:44

31

In MySQL : show global variables like '%slow%';

Update : here's a link to the manual: link text

edited Sep 28 '11 at 20:44

RolandoMySQLDBA

answered Jan 11 '11 at 20:04

SteveHarville

1

Can you link to the manual for a short answer like this? – Brian Ballsun-Stanton Jan 12 '11 at 01:59

score 24 · Accepted Answer · answered Jan 03 '11 at 21:37

24

You can find it in the default directory, depending on your install. For instance, on my Red Hat, it's /var/log/mysql/

Query time is time, in seconds, over which it should start recording. This can be done at startup and at runtime.

log-slow-queries = /var/log/mysql/mysql-slow.log

long_query_time = 1

answered Jan 03 '11 at 21:37

David Hall

5

At my site, I discovered someone has set log_slow_queries=ON. So I have a file in my datadir called ON containing the log. That was confusing... – Gaius Jan 03 '11 at 22:01
6

Note that log-slow-queries is deprecated as of 5.1.29. The one to use thereafter is slow-query-log. – Riedsio Jan 13 '11 at 22:19
1

Also note that beginning with MySQL 5.1.21, a resolution of microseconds is supported when logging to a file. – Riedsio Jan 13 '11 at 22:25

score 7 · Answer 3 · answered Jan 13 '11 at 22:24

These are the pertinent options (and settings) I generally have/use in all my my.cnfs to log slow queries:

log_output=FILE
slow_query_log=1
slow_query_log_file=/var/log/mysql/mysql.slow 
long_query_time=0.001 
log-queries-not-using-indexes=0

Beginning with MySQL 5.1.21 ... a resolution of microseconds is supported when logging to a file.

RolandoMySQLDBA · Answer 4 · 2011-09-28T20:44:18.450

3

Here is something to consider as well :

If you use the option

log-output=TABLE

in you /etc/my.cnf file, look for the slow log to be a CSV storage engine based table located in, of all places, the mysql schema.

This affects the general log as well, once you enable it.

edited Sep 28 '11 at 20:44

answered Feb 12 '11 at 03:46

RolandoMySQLDBA

Can you log slow queries to table but the "normal" log into a file? – surfmuggle Nov 11 '20 at 20:31
@surfmuggle Yes you can. If you put log-output=FILE,TABLE. that would do it !!! You must restart mysql to implement this. – RolandoMySQLDBA Nov 11 '20 at 21:23

score 3 · Answer 5 · answered Jan 03 '11 at 22:09

3

Search your mysqld config file (usually, /etc/my.cnf)

At your shell:

grep slow /etc/my.cnf

answered Jan 03 '11 at 22:09

randomx

5 Answers5