Hi Milan, I can see many ways of accomplish what you want: * I'm almost sure mk-query-digest will allow you to do so; * Either crop the slow query log for the desired timespan (that's a couple of shell scripting commands) and run mk-query-digest against it; * Set the query log file to a filename which is a link to /dev/null and set a cron script to relink it to a real filename at noon and another to relink it to /dev/null at 1pm - and then run the scripts you want. * In newer versions you can log the slow queries to tables for analysis; * Ultimately, you can also try a patched version of mysqldumpslow I was using for some time, explained here: http://gpshumano.blogs.dri.pt/2009/07/04/analysing-mysql-slow-queries/
In the last two options you'll be logging to a table, so it will be easy to select a timed range of queries for consideration. Hope that helps, -NT Quoting Milan Andric <mand...@gmail.com>: > Thanks for the quick replies guys. I won't be pulling queries our of > Drupal anytime soon. The optimizations I will do are minimal. Sounds > like we might just have to live with mediocre performance for now. > > I will definitely looks further at maatkit though. I actually ran it > mk-query-digest on my slow log and it's pretty amazing output. Lots > there but it might take me a while to digest it all. And it does have > a time span for the queries it spots, like: > > # Time range 2009-07-31 06:46:48 to 2009-07-31 12:51:21 > > Which is pretty helpful, but ideally I would like to pass args to > mk-query-digest to list specific queries that were slow between noon > and 1pm for example. If anyone happens to know how to that it would > be helpful. Otherwise I will keep grokking maatkit tools. > > Thanks, > > Milan > > > On Fri, Jul 31, 2009 at 3:14 PM, Johan De Meersman<vegiv...@tuxera.be> > wrote: > > On Fri, Jul 31, 2009 at 8:14 PM, Milan Andric <mand...@gmail.com> wrote: > > Hello, > > > > I'm serving a burly Drupal install and at some points throughout the > > day the mysql threads go way up and iowait peaks. I'm not sure which > > is causing which but during this time the server is unresponsive. I > > would like to determine if there is a poorly optimized query causing > > this. > > > > Drupal is a disaster :-) > > > > I'm running a dozen drupals, and we've spent the last eight months heavily > > optimizing every aspect. It's reasonably good now, but I'd still like to > > move away from it. > > > > Drupal wants to remain compatible with multiple databases, notably both > > MySQL and Postgres, and for v7 also Oracle. This means that they can't > > optimize their DB layer and use the fancy tricks of a single DB, but must > do > > things in ways that are compatible with all of them. Postgres doesn't have > > autoincrement ? No autoincrement. Mysql doesn't have sequences ? No > > sequences. > > > > Some points: > > - Drupal uses it's own internal unique ID system, not autoincrement, for > a > > number of things. This means that every insert that uses this locks all > > other inserts that use this. > > - Drupal has the bothersome tendency to do full table locks around some > > inserts. This means that even if you move to InnoDB, you'll still get full > > table locks. We patched this out according to info found on drupal.org and > > other sites. > > - Drupal's innate caching mechanisms are DB bound. Fun and dandy, but > > rather irritating if as soon as a busy page expires, a hundred threads all > > try to update the same table at the same time. We implemented Memcached. > > Patches, at least partial ones, are on drupal.org, but I know we did more > > and better in-house. > > - Drupal can cache fine for anonymous users, but once you're logged in, > > it's nearly impossible to cache. We worked around this by basically making > > 'static' cacheable pages, and pulling any dynamic content in through AJAX. > > - Get rid of Drupal's views (in drupal, that is, not wat is called a view > > in a database). They generate horribly inefficient queries. > > - Full text search modules use MySQL's full text indices, but that's not > > the best way of doing things. We implemented Sphinx search, there's an > > existing drupal module for integration. > > > > There's lots more that was done, but I can't provide all that info because > > a) it's company internal, and b) because I'm not a developer and thus > don't > > know half of it :-) > > > > Suffice it to say, I don't like drupal for high-traffic interactive sites. > > Get away from it if you can. > > > > > > > > > >> I'm logging slow queries but is there a way to see when the > >> slow queries take place also? I'd like to know what queries are being > >> processed during this window of poor response time, usually around > >> noon local time. > > > > If you want more than just the slow queries, you'll have to enable the > full > > log. Be aware that this has noticeable impact on performance, and will > spam > > your disks. Log on different spindles if able, and monitor your disk usage > > carefully - mysql stops functioning if it can't write logs. > > > > > > > > > > -- > > Celsius is based on water temperature. > > Fahrenheit is based on alcohol temperature. > > Ergo, Fahrenheit is better than Celsius. QED. > > > > -- > MySQL General Mailing List > For list archives: http://lists.mysql.com/mysql > To unsubscribe: http://lists.mysql.com/mysql?unsub=nuno.tava...@dri.pt > > -- Nuno Tavares +351 93 618 40 86 dri Consultoria Informatica -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=arch...@jab.org
