On Fri, 2007-11-30 at 17:41 +1100, Russell Smith wrote: > Simon Riggs wrote: > > On Tue, 2007-11-27 at 18:06 -0500, Pablo Alcaraz wrote: > > > >> Simon Riggs wrote: > >> > >>> All of those responses have cooked up quite a few topics into one. Large > >>> databases might mean text warehouses, XML message stores, relational > >>> archives and fact-based business data warehouses. > >>> > >>> The main thing is that TB-sized databases are performance critical. So > >>> it all depends upon your workload really as to how well PostgreSQL, or > >>> another other RDBMS vendor can handle them. > >>> > >>> > >>> Anyway, my reason for replying to this thread is that I'm planning > >>> changes for PostgreSQL 8.4+ that will make allow us to get bigger and > >>> faster databases. If anybody has specific concerns then I'd like to hear > >>> them so I can consider those things in the planning stages > >>> > >> it would be nice to do something with selects so we can recover a rowset > >> on huge tables using a criteria with indexes without fall running a full > >> scan. > >> > >> In my opinion, by definition, a huge database sooner or later will have > >> tables far bigger than RAM available (same for their indexes). I think > >> the queries need to be solved using indexes enough smart to be fast on disk. > >> > > > > OK, I agree with this one. > > > > I'd thought that index-only plans were only for OLTP, but now I see they > > can also make a big difference with DW queries. So I'm very interested > > in this area now. > > > > > If that's true, then you want to get behind the work Gokulakannan > Somasundaram > (http://archives.postgresql.org/pgsql-hackers/2007-10/msg00220.php) has > done with relation to thick indexes. I would have thought that concept > particularly useful in DW. Only having to scan indexes on a number of > join tables would be a huge win for some of these types of queries. Hmm, well I proposed that in Jan/Feb, but I'm sure others have also. I don't think its practical to add visibility information to *all* indexes, but I like Heikki's Visibility Map proposal much better. > My tiny point of view would say that is a much better investment than > setting up the proposed parameter. They are different things entirely, with dissimilar dev costs also. We can have both. > I can see the use of the parameter > though. Good -- Simon Riggs 2ndQuadrant http://www.2ndQuadrant.com ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org
