ITAGAKI Takahiro wrote: > Bruce Momjian <pgman@candle.pha.pa.us> wrote: > > > > - Is fillfactor useful for hash and gist indexes? > > > I think hash does not need it, but gist might need it. > > > > Not sure. We don't know what type of index a GIST will be so we have no > > way of knowing. I am thinking we can implement just btree now and the > > GIST folks can add it later if they want. My guess is that each GIST is > > going to behave differently for different fill-factors, so if allow it > > to be set for GIST, GIST developers can pull the value if they want. > > My understanding about hash was wrong. It uses fill factor of 75%, which is > hard-coded. On the other hand, GIST has no ability to control fill factor > currently. I'm trying to add fill factors to hash and gist, so I'll ask > index developers to review a patch in the future.
OK. > > > - Is it appropriate to use GUC variables to control fillfactors? > > > Is it better to extend CREATE INDEX / REINDEX grammar? > > > > I think it has to be part of CREATE INDEX and ALTER INDEX. > > SQL standard has no regulation for indexes, so I refered to other databases. > - Oracle and DB2 : CREATE INDEX index ON table (...) PCTFREE 30; > - MS SQL Server : CREATE INDEX index ON table (...) WITH FILLFACTOR = 70; > > PCTFREE seems to be common, so I'll extend DDL to use PCTFREE syntax. > The following two syntaxes will be able to be used. > 1. SET btree_free_percent = 30; > CREATE INDEX index ON table (...); > SET btree_free_percent = 10; -- revert > 2. CREATE INDEX index ON table (...) PCTFREE 30; > > 1 would be useful for a compatibe pg_dump format, per suggestion from Tom. I personally like FILLFACTOR, but I understand the desire to match Oracle. PCTFREE seems too abreviated for me, but it would match the GUC better, so maybe it is the best. > > Is there a use for separate node and leaf settings? > > We should use different settings for leaf and node, but it may confuse users. > So I'll simplify the setting as follows: > node_free_percent = Min(30%, 3 * leaf_free_percent) > When leaf_free_percent is 10%, node_free_percent is 30%. They are the same > values of the current implementation. Yes, I think that is ideal. -- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073 ---------------------------(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
