Re: pgsql: Fix another instance of unsafe coding for shm_toc_lookup failure

Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com> writes:
> On Sat, Feb 3, 2018 at 12:32 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Fix another instance of unsafe coding for shm_toc_lookup failure.

> my mistake was actually to put noError = true there when noError =
> false was called for.

Ah.

> However, it's not surprising that you drew the
> opposite conclusion (ie that it might in fact not be in the TOC),
> since the shm space is really only necessary for EXPLAIN ANALYZE.
> Perhaps I should make it skip setting up this shm stuff if
> !node->ss.ps.instrument, just like the equivalent Sort node code. I
> will look into that on Monday.

OK. Please send in a patch to either do that or switch this call to use
noError = false. Or possibly both: shouldn't there be some other signal
path that tells the worker whether instrumentation is needed? I'll
leave it alone pending your investigation.

regards, tom lane