From: | Vadim Mikheev <vadim(at)krs(dot)ru> |
---|---|
To: | Lincoln Yeoh <lylyeoh(at)mecomb(dot)com> |
Cc: | pgsql-general(at)postgreSQL(dot)org, PostgreSQL Developers List <hackers(at)postgreSQL(dot)org> |
Subject: | Re: [GENERAL] Postgres INSERTs much slower than MySQL? |
Date: | 1999-10-22 05:52:40 |
Message-ID: | 380FFBA8.82447656@krs.ru |
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Thread: | |
Lists: | pgsql-general pgsql-hackers |
Lincoln Yeoh wrote:
>
> At 04:38 PM 20-10-1999 +0800, Vadim Mikheev wrote:
> >You hit buffer manager/disk manager problems or eat all disk space.
> >As for "modifying" - I meant insertion, deletion, update...
>
> There was enough disk space (almost another gig more). So it's probably
> some buffer manager problem. Is that the postgres buffer manager or is it a
> Linux one?
>
> Are you able to duplicate that problem? All I did was to turn off
> autocommit and start inserting.
I created table with text column and inserted 1000000 rows
with '!' x rand(256) without problems on Sun Ultra, 6.5.2
I run postmaster only with -S flag.
And while inserting I run select count(*) from _table_
in another session from time to time - wonder what was
returned all the time before commit? -:))
> >> Well anyway the Postgres inserts aren't so much slower if I only commit
> >> once in a while. Only about 3 times slower for the first 100,000 records.
> >> So the subject line is now inaccurate :). Not bad, I like it.
> >
> >Hope that it will be much faster when WAL will be implemented...
>
> What's WAL? Is postgres going to be faster than MySQL? That would be pretty
^^^^^^^^^^^^^^^^^^^^^^^
No.
> impressive- transactions and all. Woohoo!
WAL is Write Ahead Log, transaction logging.
This will reduce # of fsyncs (among other things) Postgres has
to perform now.
Test above took near 38 min without -F flag and 24 min
with -F (no fsync at all).
With WAL the same test without -F will be near as fast as with
-F now.
But what makes me unhappy right now is that with -F COPY FROM takes
JUST 3 min !!! (And 16 min without -F)
Isn't parsing/planning overhead toooo big ?!
Vadim
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