On Mon, Jan 19, 2015 at 5:46 PM, Cédric Villemain <ced...@2ndquadrant.com> wrote:
> Le lundi 19 janvier 2015 08:24:08 Robert Haas a écrit : > > > On Sat, Jan 17, 2015 at 4:49 AM, Alexander Korotkov > > > > > > <aekorot...@gmail.com> wrote: > > > > I already wrote quite detailed explanation of subject. Let mel try > > > > to > > > > explain in shortly. GIN is two level nested btree. Thus, GIN would > > > > have absolutely same benefits from fillfactor as btree. Lack of > > > > tests showing it is, for sure, fault. > > > > > > > > However, GIN posting trees are ordered by ItemPointer and this makes > > > > some specific. If you have freshly created table and do > > > > inserts/updates they would use the end of heap. Thus, inserts would > > > > go to the end of GIN posting tree and fillfactor wouldn't affect > > > > anything. Fillfactor would give benefits on HOT or heap space > > > > re-usage. > > > > > > Ah, OK. Those tests clarify things considerably; I see the point now. > > > > So I do. > > > > Alexander said: > > 1) In order to have fully correct support of fillfactor in GIN we need to > rewrite GIN build algorithm. > > 2) Without rewriting GIN build algorithm, not much can be done with entry > tree. However, you can implement some heuristics. > > > > The patch is 2), for the posting tree only ? > Yes, it's just for posting tree. ------ With best regards, Alexander Korotkov.
