Just a small thought. If the file decision is preferred, then it might be worth considering to create a file per tablespace.
Thanks, Gokul. On Nov 9, 2007 7:15 PM, Simon Riggs <[EMAIL PROTECTED]> wrote: > On Fri, 2007-11-09 at 13:27 +0000, Heikki Linnakangas wrote: > > Alvaro Herrera wrote: > > > One idea is to have the first FSM page be movable, and create it by > > > extending the table when as soon as it's first "needed" (this would be > > > the first vacuum that needs to record free space on the table). The > > > page number used is recorded in the relcache entry (and pg_class). > > > Further FSM pages use a fixed position. If the table grows beyond the > > > first fixed position before creating the first FSM page, reserve that > > > one for the first FSM page and record that. > > > > It wouldn't need to be movable. We could just allocate the first FSM > > page when the table grows bigger than say 10 pages. The first FSM page > > would always be at block 11, and it could store the free space > > information for pages 0-10 as well. > > > > I'm not particularly worried about the bloat on small tables, though. If > > a table that used to take 8k bytes now takes 16k, who cares. You > > wouldn't need to load the FSM pages to shared buffers unless the FSM is > > actually used. > > I'm more worried about the shared memory space we would waste if we have > FSM blocks for very small tables. > > Now we use very few bytes per block, which is memory efficient for lots > of small tables and bad with lots of large tables. Putting the FSM in > blocks might change that the other way around. > > -- > Simon Riggs > 2ndQuadrant http://www.2ndQuadrant.com > > > ---------------------------(end of broadcast)--------------------------- > > TIP 1: if posting/reading through Usenet, please send an appropriate > subscribe-nomail command to [EMAIL PROTECTED] so that your > message can get through to the mailing list cleanly > ---------------------------(end of broadcast)--------------------------- TIP 7: You can help support the PostgreSQL project by donating at http://www.postgresql.org/about/donate
