On Mon, Aug 20, 2012 at 6:44 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Robert Haas <robertmh...@gmail.com> writes: >> On Mon, Aug 20, 2012 at 4:27 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: >>> Surely we could just prevent creation of the FSM until the table has >>> reached at least, say, 10 blocks. >>> >>> Any threshold beyond one block would mean potential space wastage, >>> but it's hard to get excited about that until you're into the dozens >>> of pages. > >> I dunno, I think one-row tables are pretty common. > > Sure, and for that you don't need an FSM, because any row allocation > attempt will default to trying the last existing block before it extends > (see RelationGetBufferForTuple). It's only once you've got more than > one block in the table that it becomes interesting. > > If we had a convention that FSM is only created for rels of more than > N blocks, perhaps it'd be worthwhile to teach RelationGetBufferForTuple > to try all existing blocks when relation size <= N. Or equivalently, > hack the FSM code to return all N pages when it has no info.
Now that's an idea I could get behind. I'd pick a smaller value of N than what you suggested (10), perhaps 5. But I like it otherwise. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
