From: Tom Lane <tgl@sss.pgh.pa.us>
To: Hannu Krosing <hannu@tm.ee>
Cc: Jan Wieck <janwieck@Yahoo.com>
Cc: D. Johnson <dspectra@home.com>
Cc: pgsql-interfaces@postgresql.org
Subject: Re: Re: Postgres and Oracle differences and questions
Date: Wed, 07 Feb 2001 10:36:18 -0500
Message-ID: <28278.981560178@sss.pgh.pa.us> (raw)
In-Reply-To: <3A8155DF.80007@tm.ee>
References: <200102071006.FAA02488@jupiter.greatbridge.com>
<3A8155DF.80007@tm.ee>
Hannu Krosing <hannu@tm.ee> writes:
> What are the performance implications - is it 1.01, 10 or 1000 times
> slower than accessing the same file from fs for files in the range of
> typical Office documents (0.2-20M) ?
I think that's a meaningless question unless you specify a particular
usage pattern --- but in any case, I doubt anyone has tried to
characterize it that way. Feel free to run some experiments and tell
us about your results...
> Will updating one non-toasted field in a tuple copy the toasted one
> as well, or is only the reference copied ?
It copies the reference, see toast_insert_or_update in
src/backend/access/heap/tuptoaster.c.
Speaking of which, though, it looks like an update or insert will
forcibly uncompress (and later recompress) a compressed-in-line datum,
which seems like a waste of cycles to me. Jan, shouldn't the test for
VARATT_IS_EXTENDED at line 357 instead read VARATT_IS_EXTERNAL?
regards, tom lane
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To: pgsql-interfaces@postgresql.org
Cc: tgl@sss.pgh.pa.us, hannu@tm.ee, janwieck@Yahoo.com, dspectra@home.com
Subject: Re: Re: Postgres and Oracle differences and questions
In-Reply-To: <28278.981560178@sss.pgh.pa.us>
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