Re: Fillfactor for GIN indexes

Le lundi 19 janvier 2015 08:24:08 Robert Haas a écrit :
> On Sat, Jan 17, 2015 at 4:49 AM, Alexander Korotkov
>
> <aekorotkov(at)gmail(dot)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 ?

Thanks!
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