Ühel kenal päeval, T, 2006-07-25 kell 13:06, kirjutas Tom Lane: > "Luke Lonergan" <[EMAIL PROTECTED]> writes: > > I think we do know, have you reviewed the results in the briefing? > > I find those results moderately unconvincing, primarily because they > are based on choosing the least efficient possible data representation > (viz char(n)), and thus the btree indexes suffer severe and quite > artificial bloat.
hmm, maybe this should be fixed in btree then ? do we really need to store padding blanks in btree ? > A database schema chosen with even minimal attention > to PG-specific tuning would probably have btree indexes half the size. > That wouldn't completely eliminate the performance differential shown, > but it would bring it down into the ballpark where you have to question > whether it makes sense to support another index AM. It still depends on your data volumes. if you spend lots and lots of $ on hardware just to store surplus index bloat, it may be worth it. Remember, that the bizgres folks develop these things for real-world datawarehousing, where saving a few (tens or hundreds of) terabytes of storage and corresponging amount of RAM is a real win. > The reason I have such high sales resistance is that we've carried the > hash and rtree AMs for years, hoping that someone would do the work to > make them actually worth using, with little result. What would be the use-case for hash indexes ? And what should be done to make them faster than btree ? I know that they are not wal-logged, but this is beside the point for DWH apps. and was'nt the rtree index recently deprecated in favour of GIST implementation of the same ? > I don't want any > more second-class-citizen index AMs, and that's why I'm questioning > what the scope of applicability of bitmap indexes really is. They need > to be popular enough that people will be motivated to work on them, > or they shouldn't be in core. Is there an easy way to put them into contrib/ for some test period so that they can become popular among mainstream postgresql users ? -- ---------------- Hannu Krosing Database Architect Skype Technologies OÜ Akadeemia tee 21 F, Tallinn, 12618, Estonia Skype me: callto:hkrosing Get Skype for free: http://www.skype.com ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend