Re: Fillfactor for GIN indexes

On Tue, Feb 24, 2015 at 5:15 PM, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
wrote:

> I hoped lowering the fillfactor will improve this, but fillfactor=75 had
> pretty much no effect in this case. Is that expected for this kind of
> workload? I see the previous discussion talked about random updates, not
> inserts, so maybe that's the culprit?
>

Yes. Since posting trees are ordered by item pointers, you can get benefit
of fillfactor only if you use some item pointers lower than item pointers
already in use. You can still get benefit in the insert case but you should
have already some free space in the heap (perhaps do some deletes and
vacuum).

Actually, this is narrowing benefit from GIN fillfactor. Probably, that
means that we should still have default value of 100. But I think GIN
fillfactor still might be useful.

------
With best regards,
Alexander Korotkov.