am 07.12.2005, um 18:01:51 +0100 mailte Alexander Scholz folgendes: > Dear NG, > > I have a serious performance flaw, when using postgresql 8.1 (other > versions haven't been tested) with libpq. When executing a > > select * from "xyz" 1) > > and "xyz" contains 300'000 records, it takes more than 60 seconds for the The same question was yesterday on [pgsql-de-allgemein] ;-) > query just to complete. First I thought it is a performance problem of the > server, but then we noticed an enormous amount of TCP/IP packets that are > beeing received in that (waiting)time. The memory usage of my process, > while waiting for the query to complete, bumps up to more than 300MB, the > CPU usage goes up to 100%! It seems as if libpq would be receiving the > complete resultset from the server _before_ returning from the query > execution! (Even then 300MB seems for me to be too much, but that's not the > point!) Just to ensure: I didn't perform ANY _fetch_ so far! It's just > about executing the query. > > Does anybody have any idea, what's going on here? You have selected _ALL_ records, you got all records. Thats the point. > When doing the query in pgAdmin III it also takes that awful long time and > pgAdmin III memory usage also goes up to over 300 MB. We specified in > pgAdmin III to fetch only 1 row, thus _filling_ the grid cannot be the > reason there. The query there took 115 seconds just to complete. :-( > > Can anybody help me out?!? I'd appreciate even just a hint or reference to > somewhere else. We already googled "memory and libpq" but the first 200 > hits (sigh) didn't give any useful hint in that respect... You can use a CURSOR to walk through the result. HTH, Andreas -- Andreas Kretschmer (Kontakt: siehe Header) Heynitz: 035242/47212, D1: 0160/7141639 GnuPG-ID 0x3FFF606C http://wwwkeys.de.pgp.net === Schollglas Unternehmensgruppe ===
