Re: Parallel Index-only scan

I reviewed the patch. Overall it looks fine to me.

One comment,

>- if (index->amcanparallel &&
>- !index_only_scan &&
>+ if ((index->amcanparallel ||
>+ index_only_scan) &&

Why do we need to check for index_only_scan in the above condition. IIUC,
index->amcanparallel is necessary for
parallel index scan to be chosen. We cannot chose parallel index only scan
if index_only_scan is happening
without worrying about index->amcanparallel value. So OR-ing
index->amcanparallel with index_only_scan is probably not
correct.

Thank you,
Rahila Syed

On Thu, Feb 16, 2017 at 1:06 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

> On Thu, Jan 19, 2017 at 7:07 AM, Rafia Sabih
> <rafia(dot)sabih(at)enterprisedb(dot)com> wrote:
> > Please find the attached file rebased patch of parallel index-only
> > scan on the latest Parallel index-scan patch [1].
>
> This again needs minor rebasing but basically looks fine. It's a
> pretty straightforward extension of the parallel index scan work.
>
> Please make sure that this is pgindent-clean - i.e. that when you
> pgindent the files that it touches, pgindent doesn't change anything
> of the same parts of the file that you've changed in the patch. Also,
> I believe Amit may have made some adjustments to the logic in
> nodeIndexScan.c; if so, it would be good to make sure that the
> nodeIndexOnlyScan.c changes match what was done there. In particular,
> he's got this:
>
> if (reset_parallel_scan && node->iss_ScanDesc->parallel_
> scan)
> index_parallelrescan(node->iss_ScanDesc);
>
> And you've got this:
>
> + if (reset_parallel_scan)
> + index_parallelrescan(node->ioss_ScanDesc);
>
> There might be some other inconsistencies as well that I didn't notice
> on a quick look.
>
> --
> Robert Haas
> EnterpriseDB: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company
>