Hi all, On Mon, 2010-02-22 at 10:29 +0000, Greg Stark wrote: > On Mon, Feb 22, 2010 at 8:18 AM, Gokulakannan Somasundaram > <gokul...@gmail.com> wrote: > > a) IOT has both table and index in one structure. So no duplication of data > > b) With visibility maps, we have three structures a) Table b) Index c) > > Visibility map. So the disk footprint of the same data will be higher in > > postgres ( 2x + size of the visibility map). > > These sound like the same point to me. I don't think we're concerned > with footprint -- only with how much of that footprint actually needs > to be scanned.
For some data the disk foot-print would be actually important: on our data bases we have one table which has exactly 2 fields, which are both part of it's primary key, and there's no other index. The table is write-only, never updated and rarely deleted from. The disk footprint of the table is 30%-50% of the total disk space used by the DB (depending on the other data). This amounts to about 1.5-2TB if I count it on all of our DBs, and it has to be fast disk too as the table is heavily used... so disk space does matter for some. And yes, I put the older entries in some archive partition on slower disks, but I just halve the problem - the data is growing exponentially, and about half of it is always in use. I guess our developers are just ready to get this table out of postgres and up to hadoop... Cheers, Csaba. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
