Re: Re: Tables grow in size when issuing UPDATEs! Why??

From: Lincoln Yeoh <lyeoh(at)pop(dot)jaring(dot)my>
To: Daniel ?erud <zilch(at)home(dot)se>, pgsql-general(at)postgresql(dot)org
Subject: Re: Re: Tables grow in size when issuing UPDATEs! Why??
Date: 2001-03-29 01:07:34
Message-ID: 3.0.5.32.20010329090734.0081dca0@192.228.128.13
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At 09:26 PM 28-03-2001 GMT, Daniel ?erud wrote:
>
>I noticed it greatly affects the speed.
>Is there some way you can turn that feature off as I am
>doing speed analysis of postgresql (well, i'm kinda
>tweaking). How often should you run it? I guess it is bad to
>run it after every update.
>
>Another thought: doing _only_ inserts and selects wont
>affect the speed of the db?
>

Yeah. I also noticed that update + indexed select repeatedly on the same
row slows down over time, whereas insert + indexed select doesn't seem to
slow down for some reason. Maybe it has something to do with the indexes,
or the MVCC thingy - scanning through multiple expired rows.

The speed goes down quite significantly from the initial peak, so
benchmarks on a pristine database aren't really reliable for real world
scenarios unless you vacuum every 10000 updates or so ;). But it's a shame
because Postgres is blazingly fast at the start.

Link.

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