Re: pgsql: SQL/JSON: Avoid initializing unnecessary ON ERROR / ON EMPTY ste

On Fri, Sep 6, 2024 at 12:07 PM Amit Langote <amitlan@postgresql.org> wrote:
> SQL/JSON: Avoid initializing unnecessary ON ERROR / ON EMPTY steps
>
> When the ON ERROR / ON EMPTY behavior is to return NULL, returning
> NULL directly from ExecEvalJsonExprPath() suffices. Therefore, there's
> no need to create separate steps to check the error/empty flag or
> those to evaluate the the constant NULL expression.  This speeds up
> common cases because the default ON ERROR / ON EMPTY behavior for
> JSON_QUERY() and JSON_VALUE() is to return NULL.  However, these steps
> are necessary if the RETURNING type is a domain, as constraints on the
> domain may need to be checked.
>
> Reported-by: Jian He <jian.universality@gmail.com>
> Author: Jian He <jian.universality@gmail.com>
> Author: Amit Langote <amitlangote09@gmail.com>
> Discussion: https://postgr.es/m/CACJufxEo4sUjKCYtda0_qt9tazqqKPmF1cqhW9KBOUeJFqQd2g@mail.gmail.com
> Backpatch-through: 17
>
> Branch
> ------
> master
>
> Details
> -------
> https://git.postgresql.org/pg/commitdiff/3a97460970f344660971ee75d7f5a181bf87f633
>
> Modified Files
> --------------
> src/backend/executor/execExpr.c | 30 ++++++++++++++++++++++--------
> 1 file changed, 22 insertions(+), 8 deletions(-)

This or one of the other of my recent commits have broken some BF
animals, so reverting for now.

--
Thanks, Amit Langote