Re: How Postgresql Compares For Query And Load Operations

From: Mark kirkwood <markir(at)slingshot(dot)co(dot)nz>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: How Postgresql Compares For Query And Load Operations
Date: 2001-07-19 11:20:30
Message-ID: 01071923203003.02409@spikey.slithery.org
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> If Oracle really is doing a sort, it's hard to see where the speed
> difference came from --- unless you have set the tuning parameters such
> that Oracle does the sort all-in-memory whereas Postgres doesn't. Sorts
> that have to go to disk are lots slower.
>
I redid the tests ensuring everybody used 10M sort area... nothing was
significantly altered !! ( altho Postgres moved in towards the big boys on
the first 3 queries and the elapsed time for queries 4 & 5 converged )
>
>
> Hmm, I couldn't make out from your webpage exactly how you did the
> loading, or which steps are included in your timings. I see that you
> used COPY, which is good ... but did you create the indexes before or
> after COPY? What about the constraints? I also see a CLUSTER script
> --- was this used, and if so where is its time counted?
>
> regards, tom lane

My apologies for the state of the scripts ( to all you who downloaded them
for a play) - I had forgotten to complete the README and also left heaps of
test files lying about in the query directory. I have cleaned these up now !

The story is... the comparison was supposed to be simple... so no special
features ( like clustered indexes/tables, bitmap indexes, materialized views,
automatic summary tables...) just a comparison of how well each db did its
"bread and butter" operations.

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