Horton

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

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Corey Huinker <corey.huinker@gmail.com>, pgsql-hackers@postgresql.org, Nikita Glukhov <n.gluhov@postgrespro.ru>, Andrew Dunstan <andrew@dunslane.net>, David Rowley <dgrowleyml@gmail.com>
Date: 2023-02-23T19:39:53Z
Lists: pgsql-hackers 
Hi,

On 2023-02-23 13:56:56 -0500, Tom Lane wrote:
> Corey Huinker <corey.huinker@gmail.com> writes:
> > My not-ready-for-16 work on CAST( ... ON DEFAULT ... ) involved making
> > FuncExpr/IoCoerceExpr/ArrayCoerceExpr have a safe_mode flag, and that
> > necessitates adding a reserror boolean to ExprEvalStep for subsequent steps
> > to test if the error happened.
> 
> Why do you want it in ExprEvalStep ... couldn't it be in ExprState?
> I can't see why you'd need more than one at a time during evaluation.

I don't know exactly what CAST( ... ON DEFAULT ... ) is aiming for - I guess
it wants to assign a different value when the cast fails?  Is the default
expression a constant, or does it need to be runtime evaluated?  If a const,
then the cast steps just could assign the new value. If runtime evaluation is
needed I'd expect the various coerce steps to jump to the value implementing
the default expression in case of a failure.

So I'm not sure we even need a reserror field in ExprState.

Greetings,

Andres Freund

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