Re: Making jsonb_agg() faster

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>

To: jian he <jian.universality@gmail.com>

Cc: pgsql-hackers@lists.postgresql.org

Date: 2025-08-15T16:57:02Z

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 →

Fix jsonb_object_agg crash after eliminating null-valued pairs.
- ef5f559b95e2 19 (unreleased) landed
Micro-optimize datatype conversions in datum_to_jsonb_internal.
- 005a2907dc30 19 (unreleased) landed
Remove fundamentally-redundant processing in jsonb_agg() et al.
- b61aa76e4585 19 (unreleased) landed
Revise APIs for pushJsonbValue() and associated routines.
- 0986e95161ce 19 (unreleased) landed
Add a macro for the declared typlen of type timetz.
- 3628af42107d 19 (unreleased) landed

jian he <jian.universality@gmail.com> writes:
> outcontext will always be NULL in 0001.
> that means copyScalarSubstructure is never really called.
> it also means that JsonbInState->MemoryContext  was always as NULL in 00001
> maybe we don't need JsonbInState->MemoryContext in 0001
> So 0001 refactoring change would be less invasive.

I think you're missing the point: per the commit message for 0001,

    The real reason for doing it is to provide a mechanism whereby
    pushJsonbValue() can be told to construct the JsonbValue tree
    in a context that is not CurrentMemoryContext.  That happens
    when a non-null "outcontext" is specified in the JsonbInState.
    No callers exercise that option in this patch, but the next
    patch in the series will make use of it.

If we didn't add the outcontext option in this step, we'd just
have to do so in the next one.

			regards, tom lane