Re: Is it possible to have a "fast-write" Index?

From: Claudio Freire <klaussfreire(at)gmail(dot)com>
To: deavid <deavidsedice(at)gmail(dot)com>
Cc: "ktm(at)rice(dot)edu" <ktm(at)rice(dot)edu>, Gavin Flower <GavinFlower(at)archidevsys(dot)co(dot)nz>, PostgreSQL-Dev <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Is it possible to have a "fast-write" Index?
Date: 2015-06-10 22:02:24
Message-ID: CAGTBQpadaE_pykiCv3tWJ-noizLDH+u9JpUFfN=9oy=nAeetig@mail.gmail.com
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On Wed, Jun 10, 2015 at 6:01 PM, deavid <deavidsedice(at)gmail(dot)com> wrote:
> By now, my results were a bit disappointing: (comparing gin_btree against
> regular btree for a column with very low cardinality)
> - create index and updates: about 10-20% faster (i had a primary key, so
> btree unique checks may be here blurring the results)

That could be the effect of GIN's buffering (lets call it LSM? it's similar)

So that with pure btrees could get a similar speedup.

On Wed, Jun 10, 2015 at 6:01 PM, deavid <deavidsedice(at)gmail(dot)com> wrote:
> What i've found is, I was wrong on fillfactor. (Maybe something has changed
> here since postgresql 8.1). I believed a fillfactor lower than 80 will do
> more harm than good. At least that was the case 5 years ago. Now I could get
> a noticeable speedup with fillfactor=50 in the case of updating the whole
> table.

8.1 didn't have HOT. I'd bet it's that.

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