Re: reading large BYTEA type is slower than expected - Mailing list pgsql-performance

From Mark Harris
Subject Re: reading large BYTEA type is slower than expected
Date
Msg-id D7BFFE348C53EF4E8AA0698B1E395FA9085ABEE3@flybywire.esri.com
Whole thread Raw
In response to Re: reading large BYTEA type is slower than expected  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-performance
Tom,

Actually the 120 records I quoted is a mistake. Since it is a three band
image the number of records should be 360 records or 120 records for
each band.

Mark

-----Original Message-----
From: Tom Lane [mailto:tgl@sss.pgh.pa.us]
Sent: Friday, May 18, 2007 10:48 AM
To: Mark Harris
Cc: pgsql-performance@postgresql.org
Subject: Re: [PERFORM] reading large BYTEA type is slower than expected

"Mark Harris" <mharris@esri.com> writes:
> We have recently ported our application to the postgres database. For
> the most part performance has not been an issue; however there is one
> situation that is a problem and that is the initial read of rows
> containing BYTEA values that have an average size of 2 kilobytes or
> greater. For BYTEA values postgres requires as much 3 seconds to read
> the values from disk into its buffer cache.

How large is "large"?

(No, I don't believe it takes 3 sec to fetch a single 2Kb value.)

            regards, tom lane


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