Horton

Re: PG 15 (and to a smaller degree 14) regression due to ExprEvalStep size

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Andrew Dunstan <andrew@dunslane.net>
Cc: Andres Freund <andres@anarazel.de>, Tom Lane <tgl@sss.pgh.pa.us>, David Rowley <dgrowleyml@gmail.com>, Peter Geoghegan <pg@bowt.ie>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Nikita Glukhov <n.gluhov@postgrespro.ru>
Date: 2022-06-23T07:38:12Z
Lists: pgsql-hackers 
On Tue, Jun 21, 2022 at 05:41:07PM -0400, Andrew Dunstan wrote:
> On 2022-06-21 Tu 17:25, Andres Freund wrote:
>> On 2022-06-21 17:11:33 -0400, Andrew Dunstan wrote:
>>> I and a couple of colleagues have looked it over. As far as it goes the
>>> json fix looks kosher to me. I'll play with it some more.
>>
>> Cool.
>>
>> Any chance you could look at fixing the "structure" of the generated
>> expression "program". The recursive ExecEvalExpr() calls are really not ok...

By how much does the size of ExprEvalStep go down once you don't
inline the JSON structures as of 0004 in [1]?  And what of 0003?  The
JSON portions seem like the largest portion of the cake, though both
are must-fixes.

> Yes, but I don't guarantee to have a fix in time for Beta2.

IMHO, it would be nice to get something done for beta2.  Now the
thread is rather fresh and I guess that more performance study is 
required even for 0004, so..  Waiting for beta3 would a better move at
this stage.  Is somebody confident enough in the patches proposed?
0004 looks rather sane, seen from here, at least.

[1]: https://www.postgresql.org/message-id/20220617200605.3moq7dtxua5cxemv@alap3.anarazel.de
--
Michael

Commits

  1. JSON_TABLE: Add support for NESTED paths and columns

  2. Add basic JSON_TABLE() functionality

  3. Add SQL/JSON query functions

  4. Add soft error handling to some expression nodes

  5. Adjust populate_record_field() to handle errors softly

  6. Refactor code used by jsonpath executor to fetch variables

  7. Add more SQL/JSON constructor functions

  8. SQL/JSON: support the IS JSON predicate

  9. SQL/JSON: add standard JSON constructor functions

  10. Add static assertion ensuring sizeof(ExprEvalStep) <= 64 bytes

  11. Remove size increase in ExprEvalStep caused by hashed saops

  12. pgstat: reduce timer overhead by leaving timer running.

  13. expression eval: Fix EEOP_JSON_CONSTRUCTOR and EEOP_JSONEXPR size.

  14. SQL/JSON query functions

  15. Speedup ScalarArrayOpExpr evaluation