hi, thanks for your comments on this. On Thursday 16 July 2009 15:05:58 you wrote: > In response to Janning Vygen <vygen@xxxxxxxxxxx>: > > hi, > > > > http://archives.postgresql.org/pgsql-general/2009-03/msg00581.php > > > > This was my suggestion about introducing a statment to get a sample of > > SQL statements. Nobody answered yet. Why not? i think my suggestion would > > help a lot. Or was it kind of stupid? > > For my part, I don't think this would be useful. > > Since most of your queries are run by software, you're going to see a > fairly predictable pattern to the queries, which means your sampling isn't > going to be anywhere near random, thus it will still be inaccurate and > incomplete. I dont think so. In my use case i will get a good sampling of queries as I could keep my log_sample running over long period of time. The sampling is in any case much better than with log_minduration while logging all statement is not acceptable in production. > In my experience, I've found that enabling full logging for a short time > (perhaps a few hours) gathers enough data to run through tools like > pgFouine and find problem areas. It is not possible for us. Logging millions of statements take too much time. > Also, we have development servers that > run automated tests, and since it's not critical that they be performant, > we can run full query logging on them all the time. But you dont run the real use cases with automated tests. There so many factors involved in real time: caching, concurrency, data, peaktime, deadlocks, doubleclicks, robots etc. that you just can't reproduce it on a development system without lots of effort. > Additionally, we make > sure our production systems have enough hardware behind them that we can > add additional tasks without it affecting production use. that's nice, but not everybody can afford it. Of course i would love to log every statement. But do you really log every statement in production? I guess not. > All of these are (in my opinion) better approaches to the problem than > yet another arbitrary query filtering technique. I mean, logging only > the most time-consuming queries is already arbitrary enough (as you > already stated). With log_min duration i get only most time-consuming queries. With log sample i can detect if there is a fast query which is called to often. This is impossible today. Again: for my use case it makes sense to have a log_sample feature. kind regards Janning -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
