On Thu, Sep 08, 2005 at 06:45:33AM +0400, Leonid Safronie wrote: > Hi, ppl > > Is there any way to do SELECTs with different priorities? > > Once a month I need to do some complex reports on table with over 7 > billion rows, which implies several nested SELECTS and grouping (query > runs over 20 minutes on P4/2.4GHz). Concurrently, there are over 50 > processes updating tables in the same database, including table being > SELECTed to do monthly report. The issue is that response time for > these 50 processes is very important unlike for report generation, and > time spent by these processes while report running is unacceptable for > my production environment (response time grows from 1-3 seconds up to > 1-2 minutes). > > Is there any way to give different priorities to different > queries/transactions, as it's done for VACUUMing (vacuum_cost_* > options in config file)? You can try running the select from a process that's niced via the OS; some OS's will take nice into account when scheduling IO. But there is currently no mechanism to provide this capability from within PostgreSQL. There should probably be a TODO for this, since it's something that's asked about fairly often. * Provide a means for individual queries to be run at a lower priority While nice allows this for CPU-bound queries, it generally doesn't work for I/O bound queries. -- Jim C. Nasby, Sr. Engineering Consultant jnasby@xxxxxxxxxxxxx Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org
