Re: Hide 'Execution time' in EXPLAIN (COSTS OFF)

On Sun, Oct 12, 2014 at 11:55 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Ronan Dunklau <ronan(at)dunklau(dot)fr> writes:
>> That wouldn't solve the first problem mentioned, which is that for some
>> regression tests one may want to test the costs themselves, which is now
>> impossible with the new planning time feature.
>
> That's a bogus argument, because it was impossible before too. We have
> no such tests now, and it's unlikely we will ever add any, because costs
> inherently are platform-dependent. The reason we invented COSTS OFF in
> the first place was to make it possible to do EXPLAIN in regression tests
> without getting platform-dependent output.
>
> I have no great objection to making both COSTS OFF and TIMING OFF suppress
> the "planning time" output, if that's the consensus. I would object to
> taking away that behavior of COSTS OFF, because of the implications for
> back-patching EXPLAIN queries in regression tests.
>
> Another possibility, which would introduce less non-orthogonality into
> the switch design, is to remove the connection to COSTS OFF but say that
> planning time is only printed when execution time is also printed (ie,
> only in EXPLAIN ANALYZE). This seems to me that it would not be removing
> much functionality, because if you just did a plain EXPLAIN then you can
> take the client-side runtime (psql \timing) as a close-enough estimate
> of planning time.

That'd be fine with me. Making it controlled by COSTS and/or TIMING
would be OK with me, too. But let's do *something*.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company