Horton

Re: Using Expanded Objects other than Arrays from plpgsql

Michel Pelletier <pelletier.michel@gmail.com>

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From: Michel Pelletier <pelletier.michel@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-hackers@lists.postgresql.org
Date: 2024-11-11T21:34:06Z
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 →

  1. Allow extension functions to participate in in-place updates.

  2. Implement new optimization rule for updates of expanded variables.

  3. Detect whether plpgsql assignment targets are "local" variables.

  4. Preliminary refactoring of plpgsql expression construction.

  5. Refactor pl_funcs.c to provide a usage-independent tree walker.

  6. Generalize plpgsql's heuristic for importing expanded objects.

>
> The second expansion in matrix_out happens outside the function, so inside
> there is only the one expansion for both matrix_nvals and the assignment.
> Thank you!  All my tests continue to pass and the change seems to work well.


Hmm, well I spoke to soon looking at the wrong function without an
assignment, I've been down in gdb a bit too much and I got mixed up, here's
another function that wraps it and does an assignment, and it looks like
there is another expansion happening after the nvals but before the
assignment:

create or replace function test_expand_expand(graph matrix) returns matrix
language plpgsql as
    $$
    declare
        nvals bigint = nvals(graph);
    begin
        graph = test_expand(graph);
        return test_expand(graph);
    end;
    $$;

postgres=# select test_expand_expand(a) from test_fixture ;
DEBUG:  matrix_nvals
DEBUG:  DatumGetMatrix
DEBUG:  expand_matrix
DEBUG:  new_matrix
DEBUG:  context_callback_matrix_free
DEBUG:  matrix_nvals
DEBUG:  DatumGetMatrix
DEBUG:  expand_matrix
DEBUG:  new_matrix
DEBUG:  context_callback_matrix_free
DEBUG:  matrix_nvals
DEBUG:  DatumGetMatrix
DEBUG:  expand_matrix
DEBUG:  new_matrix
DEBUG:  context_callback_matrix_free
DEBUG:  matrix_out
DEBUG:  DatumGetMatrix
DEBUG:  expand_matrix
DEBUG:  new_matrix
DEBUG:  context_callback_matrix_free

So going back on the assumption I'm somehow not returning the right
pointer, but digging into the array code I'm pretty sure I'm following the
same pattern and tracing my code path is calling EOHPGetRWDatum when I
return the object, I can't get it to stop on DeleteExpandedObject, so I
don't think plpgsql is deleting it, I'm going to keep investigating, sorry
for the noise.

-Michel

>