Re: Performance while loading data and indexing

From: "Shridhar Daithankar" <shridhar_daithankar(at)persistent(dot)co(dot)in>
To: pgsql-hackers(at)postgresql(dot)org, pgsql-general(at)postgresql(dot)org
Subject: Re: Performance while loading data and indexing
Date: 2002-09-26 09:35:40
Message-ID: 3D932244.13502.1371B9CA@localhost
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On 26 Sep 2002 at 19:17, Justin Clift wrote:
> Shridhar Daithankar wrote:
> <snip>
> > 3) Any suggsestions for runtime as data load and query will be going in
> > parallel.
>
> That sounds unusual. From reading this, it *sounds* like you'll be
> running queries against an incomplete dataset, or maybe just running the
> queries that affect the tables loaded thus far (during the initial
> load).

That's correct. Load the data so far and keep inserting data as and when it
generates.

They don't mind running against data so far. It's not very accurate stuff
IMO...

> > fsync=true (Sad but true. Left untouched.. Will that make a difference on
> > SCSI?)
>
> Definitely. Have directly measured a ~ 2x tps throughput increase on
> FreeBSD when leaving fsync off whilst performance measuring stuff
> recently (PG 7.2.2). Like anything it'll depend on workload, phase of
> moon, etc, but it's a decent indicator.

I didn't know even that matters with SCSI..Will check out..

> fsync = off would help during the data load, but not a good idea if
> you're going to be running queries against it at the same time.

That's OK for the reasons mentioned above. It wouldn't be out of place to
expect a UPS to such an installation...

Bye
Shridhar

--
Hoare's Law of Large Problems: Inside every large problem is a small problem
struggling to get out.

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