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: Andrew Dunstan <andrew@dunslane.net>
Cc: Michael Paquier <michael@paquier.xyz>, 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: 2022-07-05T18:36:02Z
Lists: pgsql-hackers 
Hi,

On 2022-06-24 10:29:06 -0400, Andrew Dunstan wrote:
> On 2022-06-23 Th 21:51, Andres Freund wrote:
> > On 2022-06-23 16:38:12 +0900, Michael Paquier wrote:
> >> On Tue, Jun 21, 2022 at 05:41:07PM -0400, Andrew Dunstan wrote:
> >>> 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..
> > I don't think there's a whole lot of performance study needed for 0004 - the
> > current state is obviously wrong.
> >
> > I think Andrew's beta 2 comment was more about my other architectural
> > complains around the json expression eval stuff.
> 
> 
> Right. That's being worked on but it's not going to be a mechanical fix.

Any updates here?

I'd mentioned the significant space use due to all JsonCoercionsState for all
the types. Another related aspect is that this code is just weird - the same
struct name (JsonCoercionsState), nested in each other?

    struct JsonCoercionsState
    {
        struct JsonCoercionState
        {
            JsonCoercion *coercion; /* coercion expression */
            ExprState  *estate; /* coercion expression state */
        }           null,
                    string,
        numeric    ,
                    boolean,
                    date,
                    time,
                    timetz,
                    timestamp,
                    timestamptz,
                    composite;
    }           coercions;      /* states for coercion from SQL/JSON item
                                 * types directly to the output type */

Also note the weird numeric indentation that pgindent does...


> The attached very small patch applies on top of your 0002 and deals with
> the FmgrInfo complaint.

Now that the FmgrInfo is part of a separately allocated struct, that doesn't
seem necessary anymore.

- Andres

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