Re: Re: patch: fix performance problems with repated decomprimation of varlena values in plpgsql

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Pavel Stehule <pavel.stehule@gmail.com>, Noah Misch <noah@leadboat.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2011-01-19T20:52:01Z
Lists: pgsql-hackers
Robert Haas <robertmhaas@gmail.com> writes:
> I do remember that discussion.  Aside from the problem you mention, it
> also seems that maintaining the hash table and doing lookups into it
> would have some intrinsic cost.

Well, sure, but it's still far cheaper than going out to the toast table
(which will require multiple hashtable lookups, not to mention I/O and
possible lock blocking).  If we could solve the refcounting problem I
think this would be a very significant win.

			regards, tom lane