Quoting Vivek Khera <[EMAIL PROTECTED]>: > >>>>> "TL" == Tom Lane <[EMAIL PROTECTED]> writes: > > TL> Jack Orenstein <[EMAIL PROTECTED]> writes: > >> I'm looking at one case in which two successive transactions, each > >> updating a handful of records, take 26 and 18 *seconds* (not msec) to > >> complete. These transactions normally complete in under 30 msec. > > TL> I've seen installations in which it seemed that the "normal" query load > TL> was close to saturating the available disk bandwidth, and the extra load > TL> imposed by a background VACUUM just pushed the entire system's response > TL> time over a cliff. In an installation that has I/O capacity to spare, > ... > TL> I suspect that the same observations hold true for checkpoints, though > TL> I haven't specifically seen an installation suffering from that effect. > > I don't see that. But I also set checkpoint segments to about 50 on > my big server.
But wouldn't that affect checkpoint frequency, not checkpoint cost? Jack Orenstein ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program. ---------------------------(end of broadcast)--------------------------- TIP 9: the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match