Re: Parallelize correlated subqueries that execute within each worker

James Coleman <jtc331@gmail.com>

From: James Coleman <jtc331@gmail.com>

To: Michael Paquier <michael@paquier.xyz>

Cc: Robert Haas <robertmhaas@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, Amit Kapila <amit.kapila16@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>

Date: 2022-01-14T19:15:40Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Windows support in pg_import_system_collations
- bf03cfd16217 16.0 cited
Remove pessimistic cost penalization from Incremental Sort
- 4a29eabd1d91 16.0 cited

Attachments

v4-0001-Allow-parallel-LATERAL-subqueries-with-LIMIT-OFFS.patch (application/octet-stream) patch v4-0001
v4-0002-Parallel-query-support-for-basic-correlated-subqu.patch (application/octet-stream) patch v4-0002
v4-0003-Other-places-to-consider-for-completeness.patch (application/octet-stream) patch v4-0003

On Fri, Dec 3, 2021 at 2:35 AM Michael Paquier <michael@paquier.xyz> wrote:
>
> On Mon, Nov 15, 2021 at 10:01:37AM -0500, Robert Haas wrote:
> > On Wed, Nov 3, 2021 at 1:34 PM James Coleman <jtc331@gmail.com> wrote:
> >> As I understand the current code, parallel plans are largely chosen
> >> based not on where it's safe to insert a Gather node but rather by
> >> determining if a given path is parallel safe. Through that lens params
> >> are a bit of an odd man out -- they aren't inherently unsafe in the
> >> way a parallel-unsafe function is, but they can only be used in
> >> parallel plans under certain conditions (whether because of project
> >> policy, performance, or missing infrastructure).
> >
> > Right.
>
> Please note that the CF bot is complaining here, so I have moved this
> patch to the next CF, but changed the status as waiting on author.

I rebased this back in December, but somehow forgot to reply with the
updated patch, so, here it is finally.

Thanks,
James Coleman