On Thu, Jun 28, 2007 at 01:35:22AM -0700, Aaron Stone wrote: > On Thu, 2007-06-28 at 10:02 +0200, Marc Dirix wrote: > > > > > > Right, and mysql can, too. But looking at eg. the "slow squirrelmail" > > > thread on the dbmail list right now, if dbmail itsself provided timing > > > along with all the other level 5 info, there would be no need to be > > > requesting that from the original poster. That's a somewhat common > > > info > > > request, so would save time debuggging things. It wouldn't slow > > > things > > > too much (primarily the extra log message) .. and as you mentioned, > > > level > > > is slow, it's only for debugging problems, not real use. > > > > > > > As most do these sort of debugging on the production system, I would > > say every performance hit > > has to be taken with care. I would not like to put anymore strain on > > the users then necessary when > > already debugging a "slow" problem. > > How expensive can doing this ourselves this be? Two calls to time(2), > subtract, compare with some threshold value, log if it exceeds that. > Seems like a great deal because we can log slow queries at a higher > level, making it less expensive to debug problems like these.
PostgreSQL uses gettimeofday() to handle a bunch of stuff, and we've found that in some environments it's got a pretty substantial overhead. For example, EXPLAIN ANALYZE (which makes heavy use of gettimeofday()) can sometimes take 30% longer than running the query by itself. So I wouldn't just hand-waive this away. OTOH, if each time you run it you're sending a command across the wire to a database server... BTW, for performance-conscious folks, converting raw query calls into functions/procedures could produce a good gain, *especially* in cases where you're sending multiple commands to do something. -- Decibel!, aka Jim C. Nasby, Database Architect [EMAIL PROTECTED] Give your computer some brain candy! www.distributed.net Team #1828
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