Neil Conway wrote: > On Thu, 20 Jun 2002 22:50:04 -0400 (EDT) > "Bruce Momjian" <[EMAIL PROTECTED]> wrote: > > I have thought that some type of feedback from the executor back into > > the optimizer would be a good feature. Not sure how to do it, but your > > idea makes sense. It certainly could update the table statistics after > > a sequential scan. > > Search the archives for a thread I started on -hackers called "self-tuning > histograms", which talks about a pretty similar idea. The technique there > applies only to histograms, and builds the histogram based *only* upon > the data provided by the executor. > > Tom commented that it's probably a better idea to concentrate on more > elementary techniques, like multi-dimensional histograms, before starting > on ST histograms. I agree, and plan to look at multi-dimensional histograms > when I get some spare time.
I was thinking of something much more elementary, like a table that reports to have 50 blocks but an executor sequential scan shows 500 blocks. -- Bruce Momjian | http://candle.pha.pa.us [EMAIL PROTECTED] | (610) 853-3000 + If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania 19026 ---------------------------(end of broadcast)--------------------------- TIP 6: Have you searched our list archives? http://archives.postgresql.org
