From: Tom Lane <tgl@sss.pgh.pa.us>
To: obartunov@gmail.com
cc: pgsql-docs@postgresql.org
Subject: Re: a little fix for text search
In-reply-to: 
 <CAF4Au4yBWMc08FVQBA4zR_SphTgvxRWCY=dzMHWcbhgO1qGJJw@mail.gmail.com>
References: 
 <CAF4Au4w6rrH_j1bvVhzpOsRiHCog7sGJ3LSX0tY8ZdwhHT88LQ@mail.gmail.com>
 <4877.1478983756@sss.pgh.pa.us>
 <CAF4Au4yBWMc08FVQBA4zR_SphTgvxRWCY=dzMHWcbhgO1qGJJw@mail.gmail.com>
Comments: In-reply-to Oleg Bartunov <obartunov@gmail.com>
	message dated "Sun, 13 Nov 2016 00:01:46 +0300"
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <6699.1478986625.1@sss.pgh.pa.us>
Date: Sat, 12 Nov 2016 16:37:05 -0500
Message-ID: <6700.1478986625@sss.pgh.pa.us>
Precedence: bulk
Sender: pgsql-docs-owner@postgresql.org

Oleg Bartunov <obartunov@gmail.com> writes:
> On Sat, Nov 12, 2016 at 11:49 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I don't see why that stopped being appropriate?  The point is that it
>> takes a raw text input which has to be re-parsed; that's still true
>> AFAICS.

> I mean that in the past we recommended to use subselect to avoid extra
> ts_headline() call, which now, at least at 9.6, it's obsoleted and two sql
> queries call ts_headline() exactly 5 times.

Oh, I see your point: commit 9118d03a8 fixed the planner so you don't get
extra evaluations of ts_headline() in this example.  I think it's probably
still appropriate to warn that ts_headline() is expensive, but yes, the
specific example is obsolete.

			regards, tom lane


-- 
Sent via pgsql-docs mailing list (pgsql-docs@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-docs