On Mon, Nov 06, 2006 at 08:53:28PM +0000, Simon Riggs wrote: > On Fri, 2006-11-03 at 15:16 -0700, Rusty Conover wrote: > > > It doesn't appear that ANALYZE uses the specified operator class for > > producing statistics on an index when that operator class is not the > > default for the data type. This appears to be leading to poor query > > planning. > > > For speed of indexing a few million urls I'm indexing them with a > > custom data type. The data type aptly named "urlhash" has: > > Have you read the CREATE TYPE man page, specifically with regard to the > analyze_function clause? Basically, if you want anything different, you > have to write an analysis function yourself. This is what PostGIS > (www.postgis.org) does, if you want to look for specific code examples. > > ANALYZE collects stats for tables, not indexes, using the default > operator class for the datatype. So even though you've clearly specified > an opclass for the index, no stats will be collected using it. > > Alternatively, perhaps you have fallen foul of this situation? > > /* > * Can't analyze if the opclass uses a storage type > * different from the expression result type. We'd get > * confused because the type shown in pg_attribute for > * the index column doesn't match what we are getting > * from the expression. Perhaps this can be fixed > * someday, but for now, punt. > */ > > It's in the analyze.c code, but not in the docs.
Should a doc patch be in the offing here? Cheers, D -- David Fetter <[EMAIL PROTECTED]> http://fetter.org/ phone: +1 415 235 3778 AIM: dfetter666 Skype: davidfetter Remember to vote! ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq
