Slow Query Log analyzes tools
MySQL has simple but quite handy feature - slow query log, which allows you to log all queries which took over define number of seconds to execute. There is also an option to enable logging queries which do not use indexes even if they take less time (--log-queries-not-using-indexes)
Slow query log is great to spot really slow queries which are often good candidates for optimization but it has few serious problems which limits extent to which it is helpful. First - it only allows you to set slow query time in seconds, having 1 second minimum value. For most of interactive applications this is way too large - if you're developing Web application you probably want whole page to be generated less in 1 second, which issues many queries during generation. Second - if you enable option to log queries which do not use indexes it well can be flooded with fast and efficient queries, which just happen to do full table scans - for example if you would be having drop down list of states in your application and use SELECT * FROM STATES for that it would trigger and log the query.
Taking other Approach
For our clients we often need to find a queries which impact application the most. It does not always have to be slowest queries - query taking 10ms and run 1.000 times per second puts more load on server than 10 seconds query running once per second. We of course want to get rid of really slow queries but to really optimize application throughput queries which generate most of the load need to be investigated
Patching Slow Query Logging - First thing we did is created a Patch which allows you to specify slow query time in microseconds rather than seconds and allows you to log all queries in slow query log by setting long_query_time=0 This patch is adapted version of patch by Georg Richter which was made to run with recent MySQL version. Now why do not we use general log instead ? Unfortunately general logs queries before queries are executed (and even parsed) so it can't contain query execution information such as execution and lock times and number of rows examined.
After this patch is applied your slow query log starts to look like this:
-
# User@Host: root[root] @ localhost []
-
# Query_time: 0.000652 Lock_time: 0.000109 Rows_sent: 1 Rows_examined: 1
-
SELECT id FROM users WHERE name='baouong';
-
# User@Host: root[root] @ localhost []
-
# Query_time: 0.001943 Lock_time: 0.000145 Rows_sent: 0 Rows_examined: 0
-
INSERT IGNORE INTO articles (id, body,)VALUES(3558268,'sample text');
Filtering Slow Query Log - Especially after the changes to log all queries slow query log may be growing too rapidly to follow, so we implemented slow query log filter (based on parse_mysql_slow_log by Nathanial Hendler) which allows you to filter out only queries which took more than certain amount of time or examined more than certain amount of rows. This is great as allows multiple passes across same slow query log first to fix worse queries and then come to find more optimization candidates. So "tail -f mysql-slow.log | mysql_slow_log_filter -T 0.5 -R 1000" will look at queries as they come and will print out queries taking more than 0.5 seconds to execute or having more than 1000 rows examined.
Aggregating slow query log As I already mentioned besides finding slowest queries it is important to find queries which cause largest load on the server, which is with certain level of accuracy queries which take most time to execute combined. There is a tool mysqldumpslow in MySQL distribution which kind of does the thing - unfortunately being run on slow query log it does not give us information we're looking for because only slow queries will be looked at. The other problem with this tool is - it replaces all real values with "N", "S" etc placeholders, which means you can't simply copy-paste query to run EXPLAIN for it. Using this tool normally require you to keep the other window open and find query sample with real constants which matches query with placeholders to work with it.
So we came op with slow query log parser tool which works with adjusted slow query log format and which gives samples of queries after aggregation. Here is how its output looks like:
-
### 3579 Queries
-
### Total time: 3.348823, Average time: 0.000935686784017883
-
### Taking 0.000269 to 0.130820 seconds to complete
-
-
### Rows analyzed 1 - 1
-
SELECT id FROM forum WHERE id=XXX;
-
-
SELECT id FROM forum WHERE id=12345;
As you can see it also prints minimum and maximum execution times so you will be able to see if only in certain cases query takes long time to execute, for example if plan is different based on constants.
How to use this tool set ?
First be aware this patch to MySQL is not official and should be used with caution. We think it is pretty safe but it surely did not get as much battle testing as rest of MySQL Server. Good thing is - you do not have to run patched version all the time. You can just start it for a few hours to generate you query log and get back to unpatched version.
It is best if you generate this log for all your queries with long_query_time=0 so if serious portion of you load comes from very simple queries you would not lose this kind of info. Yes this will reduce your performance a bit and will require plenty of disk space which is another reason you might not wish to run it in this mode all the time. Happily you can change long_query_time without restarting server so it is easy to get sample of all queries for some period of time and then get back to logging only very slow queries.
Once you have created full log - parse it and check queries using EXPLAIN starting from most impacted onces. After you've implemented changes - repeat. Changes may help to one queries but hurt others, for example adding indexes often help SELECT queries but slow down INSERT/UPDATE ones.
Final Note: You do not have to have patched MySQL for these utilities to work. they are designed to handle standard slow query log format as well.
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59 Comments
Another way to analyse your slow queries is to generate statistics which indexes are used, just like mysql_explain_log from the standard distribution does for the general query log.
You can get mysql_explain_slow_log on willamowius.de.
Comment :: September 6, 2006 @ 5:04 am
[...] Slow Query Log analyzes tools (tags: MYSQL slowlog) [...]
Pingback :: September 11, 2006 @ 9:14 am
[...] Slow Query Log analyzes tools (tags: MYSQL slowlog) Explore posts in the same categories: 美味收藏 No related posts [...]
Pingback :: September 11, 2006 @ 9:14 am
[...] This is pretty simple approach I often use called to optimize web application performance if problem happens with few pages. If we have “everything is slow” problem looking at slow query logs may be better start. [...]
Pingback :: September 12, 2006 @ 6:44 am
[...] net) Posted by Vadim @ 2:05 am :: Uncategorized del.icio.us :: digg Comment RSS :: Trackback URI [...]
Pingback :: October 1, 2006 @ 2:05 am
Dear Peter,
Are you going to port the patch to MySQL 5.0.26?
That would be really great!
Keep up the good work,
René
Comment :: October 13, 2006 @ 1:46 pm
Rene,
The patch for 5.0.26 is here:
http://www.mysqlperformanceblog.com/files/patches/patch.slow-micro.5.0.24a.diff
Comment :: October 15, 2006 @ 1:39 pm
Sorry,
I meant:
http://www.mysqlperformanceblog.com/files/patches/patch.slow-micro.5.0.26.diff
Comment :: October 15, 2006 @ 1:40 pm
Firstly, thanks for your great work!
I used slow query log parser to analyze a slow-query-log yesterday. I seems that all of the result looking good, but I see a very-long query at last. Maybe the script has some bugs on numberic-formating? Could you help me to fix it?
OUTPUT:
### 2846 Queries
### Total time: 18446744073826.7, Average time: 6481638817.22652
### Taking 0.020004 to 18446744073709.074210.000159 seconds to complete
### Rows analyzed 0 - 762
Comment :: October 15, 2006 @ 7:26 pm
Yes, it looks like bug with numbers handling.
Could you send us part of slow-log which cause such problem ?
Comment :: October 17, 2006 @ 1:11 am
Peter, Vadim
I’m using MySQL 5.0.18. It’s not quite clear to me - does your patch fits that version.
Also, can You place somewhere/how more detailed instruction how to apply the patch.
Thanks,
M.D.
Comment :: October 25, 2006 @ 7:58 am
Hi,
I did not test with 5.0.18 - but you can try.
You need to place patch into source directory and execute
patch -p1
Comment :: October 27, 2006 @ 9:33 am
Dear Vadim,
Thank you very much for the actualised patch file!
Do you have already one for MySQL 5.0.27?
It should not be very different, because only one bug has been fixed.
http://dev.mysql.com/downloads/mysql/5.0.html
Best regards,
René
Comment :: October 29, 2006 @ 2:30 pm
Rene,
I think patch for 5.0.26 should work with 5.0.27 without any problem. I did not test though.
Will check this week or so.
Comment :: October 30, 2006 @ 8:18 am
For Your information, I’ve resently written the similar tool for regular query log to fetch the top of most popular queries.
You can check it out at http://sourceforge.net/projects/myprofi or at http://myprofi.sourceforge.net for more details.
This tool wouldn’t give you the execution time based statistics, but outputs an overview of the most frequently run queries, so you could speedup the the overall db performance by optimizing the most popular queries.
In addition I would like to mention, that Your parser does not take into account all possible string escaping ways, like doubeling quotes, escaping with slash etc. Also would be more useful to group structures like “IN (N,N,N,N,N)” into “IN (N)”.
Comment :: November 8, 2006 @ 5:04 pm
Thank you Camka,
It would be great if you make your tool to support slow query log including our format with execution time and show number of examined rows and sent rows.
Query execution time matters. Query executed most frequently may not be bottleneck.
Comment :: November 14, 2006 @ 9:18 am
[...] 介绍一个分析SQL性能的方法，使用slow-query-log对所有的SQL的执行次数、执行时间、锁定时间、涉及的行数等信息做分析，然后针对每个SQL语句的模式(类似把SQL给prepare之后的样子)做EXPLAIN，根据分析结果再做优化。之前自己在网上搜到的，在实习的时候试了一下，还是有一定效果的，否则自己拿PHP去记录SQL执行时间又杂乱又不准确。 大概步骤如下：下载MYSQL源代码，打一个patch用于输出微秒级时间和允许slow-query-log的打印阈值为0，然后得到日志之后使用一个perl脚本做分析。原文在这里，本打算详细写写，搜到一篇挺详细的大家直接看吧。 [...]
Pingback :: November 29, 2006 @ 9:34 pm
[...] More info about the patch http://www.mysqlperformanceblog.com/2006/09/06/slow-query-log-analyzes-tools/ http://bugs.mysql.com/bug.php?id=25412 [...]
Pingback :: January 12, 2007 @ 10:20 am
[...] Great news are MySQL finally released new Community release - MySQL 5.0.33, which however as promised comes without Binaries. This version also does not have any community patches yet, coming of the same tree as MySQL Enterprise. To help those who would like to use MySQL Community version but does not like to build binaries we decided to publish our build for MySQL 5.0.33 Community release. This build was done using “Generic Linux RPM” spec file on CentOS 4.4 (RHEL compatible) x86_64 Server 14M MySQL-server-5.0.33-0.glibc23.x86_64.rpm Max 3.3M MySQL-Max-5.0.33-0.glibc23.x86_64.rpm Microslow 2.6M MySQL-microslow-5.0.33-0.glibc23.x86_64.rpm Client 4.9M MySQL-client-5.0.33-0.glibc23.x86_64.rpm Shared libraries 1.7M MySQL-shared-5.0.33-0.glibc23.x86_64.rpm Headers and libraries 7.3M MySQL-devel-5.0.33-0.glibc23.x86_64.rpm Debug information 25M MySQL-debuginfo-5.0.33-0.glibc23.x86_64.rpm We added one more RPM to stantard MySQL RPMs - MySQL-microslow-5.0.33-0.glibc23.x86_64.rpm This package contains mysqld-microslow binary, the server built with our microslow patch, which enables microsecound in slow-log. More info about the patch http://www.mysqlperformanceblog.com/…nalyzes-tools/ http://bugs.mysql.com/bug.php?id=25412 Also we propose Linux (AMD64 / Intel EM64T) binaries in tar.gz archive 35M mysql-standard-5.0.33-linux-x86_64-glibc23.tar.gz The archive contains both mysqld and mysqld-microslow binaries. Source tar.gz with microslow patch23M mysql-5.0.33-microslow.tar.gz [...]
Pingback :: January 12, 2007 @ 2:50 pm
Dear Peter,
I reimplemented the mysql_slow_log_parser in PHP in order to provide an even more filtered result.
If you want me to send it, just comment this entry, because there is no attachment function here.
# Apply filter to log file once
php mysql_slow_log_parser.php mysql-slow-queries.log
Options:
-T=min_query_time Include only queries which took as long as min_query_time seconds or longer [default: 1]
-R=min_rows_examined Include only queries which examined min_rows_examined rows or more
-iu=include_user Include only queries which contain include_user in the user field [multiple]
-eu=exclude_user Exclude all queries which contain exclude_user in the user field [multiple]
-iq=include_query Include only queries which contain the string include_query (i.e. database or table name) [multiple]
–filter-duplicates Output only unique query strings with additional statistics: max_query_time, max_rows_examined, execution count [default sorting: max_query_time, max_rows_examined]
[multiple] options can be passed more than once to set multiple values.
Best regards,
René
Comment :: January 30, 2007 @ 8:23 am
Rene,
You can publish it somewhere and post a link here. If you have a trouble finding place you can send it to us and we can publish it but it is worse as we’ll need to take care of it if you decide to update it etc.
Comment :: January 30, 2007 @ 9:38 am
> 16. peter
Hei, peter,
I have finally succeeded with impementing the support for sorting by max/average/total execution time of slow queries into MyProfi. But unfortunately i have no chance to try it on patched mysql version, so i tested it just with regular slow query log. You could try the latest version of MyProfi by taking it from project’s download page. Hope it can be useful tool for measuring the database performance on query level.
Comment :: January 31, 2007 @ 1:50 am
Hello Peter,
I created a Google Code project for the MySQL Slow Query Log filter:
http://code.google.com/p/mysql-log-filter/
You can access the initial PHP5 script here (requires the PHP extension BCMath):
http://mysql-log-filter.googlecode.com/svn/trunk/mysql_filter_slow_log.php
I am planning to provide a Python version, too.
Please submit any problems or feature requests to the issue tracker on the project page.
Comment :: February 3, 2007 @ 1:55 pm
Dear Peter,
I finished the Python version, which is usually 3-5 times faster than the PHP5 version according to my personal tests, depending on the log size.
Usage Examples:
# Filter slow queries executed from other users than root for at least 3 seconds, remove duplicates and save result to file
php mysql_filter_slow_log.php -T=3 -eu=root –no-duplicates mysql-slow-queries.log
# Start permanent filtering of all slow queries from now on: at least 3 seconds or examining 10000 rows, exclude users root and test
tail -f -n 0 linux-slow.log | python mysql_filter_slow_log.py -T=3 -R=10000 -eu=root -eu=test &
# (-n 0 outputs only lines generated after start of tail)
# Stop permanent filtering
kill `ps auxww | grep ‘tail -f -n 0 linux-slow.log’ | egrep -v grep | awk ‘{print 2}’`
Comment :: February 4, 2007 @ 6:22 am
Unfortunately the comments here do not translate the “greater than” and “less than” symbols on submit.
Therefore I will use { and } as a replacement for the example above:
php mysql_filter_slow_log.php -T=3 -eu=root –no-duplicates { linux-slow.log } mysql-slow-queries.log
Comment :: February 4, 2007 @ 6:29 am
Thank you Rene,
I do not think log parser performance is that critical but I expect some people will like python parser more, especially if someone is looking to do some hacking with it.
Comment :: February 5, 2007 @ 12:52 pm
[...] first idea was to check it based on slow query log, happily the server was running MySQL with slow query log with microsecond resolution so I could check exactly which update queries take most time to execute. Unfortunately it did not [...]
Pingback :: March 7, 2007 @ 1:43 pm
[...] patches are great but I hope the patches will be continue to flow in. In fact we have submitted our slow query log with microseconds patch so we’ll see how quickly and if it will be accepted for [...]
Pingback :: March 18, 2007 @ 5:14 pm
[...] ugly little gotcha which I think few people know about. It is especially bad if you’re using tools to analyze slow query log to find what queries take up the most resources on your server - in [...]
Pingback :: March 28, 2007 @ 2:16 am
Hello,
I have set long_query_time=5 in my.cnf in mysyl server.
but although i got those queries in slow-query-log which has query_time=0 second.
means i got that query which has taken execution time is below 5 seconds.
How can i solve this issue? Pls help me…its urgent.
Thanking you,
Nilnandan Joshi
DBA
INDIA
Comment :: April 7, 2007 @ 4:45 am
[...] as you had in previous versions. We rarely would use this feature as it is incompatible with our slow query analyses patch and tools Fixing this is not trivial while staying 100% compatible to standard format as TIME type which is [...]
Pingback :: May 31, 2007 @ 5:16 am
[...] short message that patch enables microsecond resolution in slow-log (see more http://www.mysqlperformanceblog.com/2006/09/06/slow-query-log-analyzes-tools/) for 5.0.37 is available here: [...]
Pingback :: June 6, 2007 @ 4:13 am
-s=WORD
what to sort by (t, at, l, al, r, ar etc)
what’s difference between these option above?
Comment :: June 6, 2007 @ 11:58 pm
Is it possible to trace every SQL statement executed inside a procedure that is called by a client:
CREATE PROCEDURE foo()
NOT DETERMINISTIC
MODIFIES SQL DATA
COMMENT ‘Generate the required number of random battles’
BEGIN
END;
The problem is that the mysql-slow.log file only contains a trace of the call to the procedure; it does not provide any trace of every subsequent statement executed by the procedure itself:
# Time: 070607 1:23:04
# User@Host: dbo[dbo] @ localhost []
# Query_time: 0 Lock_time: 0 Rows_sent: 0 Rows_examined: 2 SET
last_insert_id=27274; CALL foo();
Is there any way to configure mysqld to trace every statement executed by MySQL?
Comment :: June 8, 2007 @ 1:51 pm
Unless I’m missing something, it seems that there is a bug in all of these patches. I’m pretty sure the line in my_time.cc that reads:
newtime/= (frequency * 1000000);
instead should be:
newtime/= (frequency / 1000000);
Please confirm!
Comment :: June 29, 2007 @ 12:04 pm
Another issue:
In the patch at:
http://www.mysqlperformanceblog.com/files/patches/patch.slow-micro.5.0.41.diff
line 2192 should read:
if ((ulong) (thd->start_timer - thd->timer_after_lock) >
not:
if ((ulong) (thd->start_time - thd->time_after_lock) >
Comment :: July 2, 2007 @ 3:40 pm
Did you think of using a mySQL Proxy script for creating the log file instead of a patch for the mySQL server?
This would make it much easier to use:
1. No need to compile the mySQL server.
2. Logging (use of mySQL Proxy) can be switched on and off by redirecting the port with iptables: http://forge.mysql.com/snippets/view.php?id=82
The mySQL Proxy script could write a logfile in the slow-log format so that your tool can use it.
Comment :: July 26, 2007 @ 8:06 am
MySQL Proxy is good but it can’t give you some information - for example number of rows examined which is quite hanly to have.
Plus for serious web sites I think minor patch is less intrusive then putting Proxy infront to handle your queries which has unknown overhead and potential side effects.
Comment :: July 26, 2007 @ 10:00 am
Hello,
Just tried applying the latest patch
- to add a ‘)’ before ‘;’ at line 1244 @ my_time.c line 1244, so it is not really a big issue. Still it would be nice if you could update the patch
http://www.mysqlperformanceblog.com/files/patches/patch.slow-micro.5.0.41.diff
to the appropriate sources
http://downloads.mysql.com/archives.php?p=mysql-5.0&v=5.0.41
and got
Error C2143: syntax error : missing ‘)’ before ‘;’ @ c:\mysql-5.0.41-slowmicro\sql-common\my_time.c line 1244
The fix is - suprisingly
Thanks,
Mads
Comment :: August 22, 2007 @ 5:14 am
Andrew,
Thank you for fixes, I applied them in patches!
Comment :: September 1, 2007 @ 8:59 am
Mads,
Thanks, I fixed that in the patches.
Comment :: September 1, 2007 @ 9:00 am
[...] Our Patch - With this patch you can get all queries logged as slow queries (with times) and as you can change [...]
Pingback :: September 13, 2007 @ 3:19 am
[...] To manage replication lag and to understand what is loading your replication it is also helpful to examine execution time of queries being replicated. Unfortunately MySQL Slow Query Log does not log replication queries. Though this is one of few slow query logging improvements you can get with our Slow Query Log patch. [...]
Pingback :: October 12, 2007 @ 12:18 pm
[...] Also, v1.7 has a –milliseconds option to make time values < 1 second print as millisecond values. This option is necessary for slow logs from servers patched with the slow query log millisecond patch. [...]
Pingback :: October 30, 2007 @ 3:22 pm
hi,
# User@Host: root[root] @ localhost []
what does this — ‘[root]‘ signify in the above statement in slow query log?
Is root@localhost is not enough?
Thanks and Regards,
Raptor.
Comment :: December 2, 2007 @ 10:22 pm
Thank you so very much for this wonderful article. I have been having an incedible amount of trouble with searches on my SMF forum timing out in Apache because mysql was taking too long to run the search query. After reading this article, I was able to find my problem was that the search query was creating a temp table and populating it with topic ID’s and then building the results off that. After analyzing the long query log, I was able to write a more much more efficient SQL statement to get the job done.
Again, thank you, thank you, thank you for posting such advanced and useful information.
Comment :: December 14, 2007 @ 9:05 pm
hi,
Would you please help me to apply patch.slow-micro.5.0.45.diff?
Shall I change mysql path in the patch?
my mysql is here : /usr/local/mysql-5.0.45-linux-i686
tanx
Comment :: December 31, 2007 @ 5:13 am
huma,
The patch is for source you need to apply it to MySQL 5.0.45 sources and recompile.
Comment :: January 3, 2008 @ 11:45 am
This is a much-needed feature - thanks for sharing it.
Just so that I understand completely, the patch makes mySQL interpret
the long_query_time specified to be in microseconds rather than in
seconds? So if I want to specify 1ms it would be 1000, and not 0.001?
Thanks
Dan
Comment :: January 17, 2008 @ 7:56 am
Right. It also allows it to be 0 to log all queries with their times.
Comment :: January 22, 2008 @ 4:43 am
[...] 1 秒钟)。可以通过 Microslow Patch 来解决这个问题(粒度可以到百万分之一秒)。这个 Patch [...]
Pingback :: April 4, 2008 @ 5:55 pm
[...] Slow Query Log analyzes tools [...]
Pingback :: April 6, 2008 @ 11:22 pm
Hello,
What should be the long_query_time for best performance?
Regards
Comment :: May 8, 2008 @ 4:39 am
[...] Slow Query Log analyzes tools | MySQL Performance Blog MySQL has simple but quite handy feature - slow query log, which allows you to log all queries which took over define number of seconds to execute. (tags: analysis article database log monitoring mysql performance tuning query slow tool) [...]
Pingback :: May 13, 2008 @ 1:35 pm
Here’s how i used this patch to benchmark our production server:
First, I enabled the general query log in my production server, and collected some data. I let it run for 60 hours (2 1/2 days), which captured peak times, and all typical usage.
I used a trick to turn off the general query log without restarting mysql - i moved the log file aside, touched a replacement, but didn’t give the mysql user write permision to it. I then used mysqladmin to flush all the logs, and when it couldn’t open a handle to the new general query log file, it simply stopped logging.
Now, get an identical piece of hardware as your production server - preferably built by clonig the HDD so you have identical OS and filesystem layout.
Recompile the same version of mysql, with this patch applied (we compile mysql from source ourselves anyway, so this is still a fair performance test). Get the database on it current up to the point you turned on the general query log.
To do this, i used a backup from a few weeks earlier, and used mysqlbinlog to extract the rest of the data from the binary logs, up until the start point. I could actually see the last line in the catchup sql matching one of the first in the general query log, so rewinded one second, and knew i was spot on.
You now have an identical server, with data in a state ready to be benchmarked.
It’s worth taking a database dump here, in case you want to run the benchmark again.
Now pump your query log acquired earlier through the below perl script. It’s very quick, very dirty, and probably very buggy, but seemed to work acceptably well in our case.
It rebuilds the timing, connections, and queries the server saw, based on the contents of query log - it creates a seperate thread for each connection, and runs each query at (about) the right time, relative to the start of the run.
That means if you have 60 hours worth of dump data, the script will run for 60 hours replaying it. This was important for us, because we have short bursts of very high load, long periods of quite low load, and even the odd moment of practically zero load. This recreates all of them, just like they were in real life.
It’s worth running this script on a seperate box with lot’s of cores - it’s very thread-hungry.
The script (replay_query_log.pl):
#!perl
use Time::Local;
use DBI();
# Setup who your DB host host, and a hash of copnnection passwords.
# You need one password entry for each user that connects
# in the logs you want to replay - you can get by grepping
# for ‘Connect’, and using cut/sed/sort/uniq liberally.
#
my $DBHOST=”slush”;
my %passwords = ( “user” => “pass”,
“reporting” => “reporting”,
“user-no-pw” => “”,
“etc” => “etc”
);
# skip the first 3 lines
();
();
();
# Process the query log, and build a couple of hashes from it:
#
# Hash 1: %queries - keyed by connection id and datetime,
# - is an array of all queries by that connection at that time.
# Hash 2: %starttime - keyed by connection id
# - contains the time the first query run by this conenction started
#
# The first hash is used to actually runt he queries, the second is used to
# avoid fork bombing the box, by only forking the processes when needed.
while ()
{
# datetime line
if(s/^(0[0-9])([01][0-9])([0-3][0-9])\s+(1?[0-9]):([0-5][0-9]):([0-5][0-9])//)
{
# Convert to unix epoch - makes date arithmetic dead easy.
$datetime = Time::Local::timelocal($6, $5, $4, $3, $2-1, “20″.$1);
$dt_min = $datetime if (($datetime < $dt_min) || !(defined $dt_min));
}
# query type line
if(s/^\s+([0-9]+) ((Query)|(Quit)|(Connect)|(Statistics)|(Binlog Dump Log))//)
{
# If we enter this loop, it means a new query/type has started.
# Save the old one (if it exists), and reinitialise the vars
# for the next
push @{$queries{$connection}{$datetime}}, $query if length($query);
$connection = $1;
$starttime{$connection} = $datetime if (($datetime $_)
{
sleep $now - $_;
}
# Now that the threads are due to start, we fork, and connect
foreach (@{$startconn{$_}})
{
my $conn = $_;
my $DBUSER = $dbun{$conn}[0];
my $DBNAME = $dbun{$conn}[1];
my $DBPASS = $passwords{$DBUSER};
my $pid = fork();
if($pid == 0)
{
###print “forked\n”;
my $dbh;
# Each connection has multiple queries, so we
# iterate the hash, waiting for the correct time
# to run each one.
# I use while(){ sleep 1 } rather than sleep n to
# avoid timing issues - this garauntees the query will
# run within +/- 0.5s of when it’s due, which is good
# enough for our purposes (usually).
foreach (sort keys %{$queries{$conn}})
{
my $dt = $_;
while((time() - $offset) connect(”DBI:mysql:database=$DBNAME;host=$DBHOST”,
“$DBUSER”, “$DBPASS”)
|| die “Couldn’t create dbh”;
}
foreach (@{$queries{$conn}{$_}})
{
my $sth = $dbh->prepare($_);
$sth->execute();
$sth->finish();
}
}
$dbh->disconnect();
###print “died\n”;
exit; # very important.
} else
{
# Don’t do this.
#waitpid($pid,0);
}
}
}
# done!!!
I got some quite interesting numbers our of it, and have learned a lot about how our database behaves.
Now - this is not a well tested script - it’s probably rife with bugs, so use with caution. Any bugfixes, enhancements, or comments - please post them back here.
Hopefully this will help some-one else out.
Comment :: June 10, 2008 @ 8:23 am
[...] Slow Query Log analyzes tools | MySQL Performance Blog (tags: article database development MySQL performance) [...]
Pingback :: June 11, 2008 @ 5:41 am
[...] Filed Under (Uncategorized) by admin on 19-06-1950 This perl script is easy to run and it rolls up the contents of your mysql-slow.log to show you not only which queries are slow, but which are called most often. Source:http://www.mysqlperformanceblog.com/2006/09/06/slow-query-log-analyzes-tools/ [...]
Pingback :: July 24, 2008 @ 8:45 am
Hi,
Is it possible to update the patch to 5.0.61? Thanks.
Comment :: August 30, 2008 @ 6:33 pm
There is patch for 5.0.62
http://www.mysqlperformanceblog.com/mysql-patches/
We also have patch in work for 5.0.67
If you need patch for 5.0.61 or any other version we can do backport on consulting basics.
Comment :: August 31, 2008 @ 11:08 am