Re: Performance problem with large resultsets (byte array 2200)

"Victor Adolfsson" <victor(at)optimumbiometrics(dot)com> writes:
> I'm having a problem with bad performance when retrieving many rows where
> each row has a 2200 long byte array (called template_compressed) and a 50
> character varying (called uniqueid)

2200 bytes is (just) long enough to trigger toasting of the entries, and
I suppose it's the extra time to fetch a toasted value that's hurting.
As long as the total row width is under 8K, you could disable toasting
by ALTER TABLE ... SET STORAGE PLAIN on all the variable-width columns
of the table. Note that this wouldn't in itself de-toast rows already
stored; so you'd have to dump/truncate/reload the table before seeing
any performance benefit.

regards, tom lane