On Fri, Feb 10, 2012 at 10:38 PM, Jim Nasby <j...@nasby.net> wrote: > On 2/7/12 8:14 AM, Alvaro Herrera wrote: >> >> Having one sequence for each toast table could be wasteful though. I >> mean, sequences are not the best use of shared buffer cache currently. >> If we could have more than one sequence data in a shared buffer page, >> things would be different. Not sure how serious this really is. > > > This would actually be an argument for supporting multiple page sizes... too > bad that's such a beast. > > FWIW, from our most complex production database: > > cnuapp_p...@postgres08.obr=# select relkind, count(*) from pg_class group by > 1; > relkind | count > ---------+------- > S | 522 > r | 1058 > t | 698 > i | 2894 > v | 221 > c | 12 > (6 rows)
Yeh, I was thinking we would do well to implement cached sequences for say first 1000 sequences. That would mean we'd only use a few thousand bytes of memory rather than 4 MB for your sequences. Idea would be to make Sequences as fast as OIDs and get rid of the weird OID code. -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
