Re: Special-case executor expression steps for common combinations

Daniel Gustafsson <daniel@yesql.se>

From: Daniel Gustafsson <daniel@yesql.se>

To: Andreas Karlsson <andreas@proxel.se>

Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Andres Freund <andres@anarazel.de>

Date: 2024-07-04T16:26:18Z

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 →

Add special case fast-paths for strict functions
- d35d32d7112b 18.0 landed
Replace EEOP_DONE with special steps for return/no return
- 8dd7c7cd0a26 18.0 landed

Attachments

v2-0002-Add-special-case-fast-paths-for-strict-functions.patch (application/octet-stream) patch v2-0002
v2-0001-Replace-EEOP_DONE-with-special-steps-for-return-n.patch (application/octet-stream) patch v2-0001

> On 20 Jun 2024, at 17:22, Andreas Karlsson <andreas@proxel.se> wrote:
> 
> On 10/12/23 11:48 AM, Daniel Gustafsson wrote:
>> Thoughts?
> 
> I have looked at the patch and it still applies, builds and passes the test cases and I personally think these optimizations are pretty much no-brainers that we should do and it is a pity nobody has had the time to review this patch.
> 
> 1) The no-return case should help with the JIT, making jitted code faster.
> 
> 2) The specialized strict steps helps with many common queries in the interpreted mode.
> 
> The code itself looks really good (great work!) but I have two comments on it.

Thanks for review!

> 1) I think the patch should be split into two. The two different optimizations are not related at all other than that they create specialized versions of expressions steps. Having them as separate makes the commit history easier to read for future developers.

That's a good point, the attached v2 splits it into two separate commits.

> 2) We could generate functions which return void rather than NULL and therefore not have to do a return at all but I am not sure that small optimization and extra clarity would be worth the hassle. The current approach with adding Assert() is ok with me. Daniel, what do you think?

I'm not sure that would move the needle enough to warrant the extra complexity.
It could be worth pursuing, but it can be done separately from this.

--
Daniel Gustafsson