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specific example is obsolete.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