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SQL/JSON: Avoid initializing unnecessary ON ERROR / ON EMPTY steps

Amit Langote <amitlan@postgresql.org>

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Commit: 77aebe9a8d3cccd4c54b43be87a38f2bae614c76
Author: Amit Langote <amitlan@postgresql.org>
Date: 2024-09-09T06:59:06Z
Releases: 17.0 
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

Files

PathChange+/−
src/backend/executor/execExpr.c modified +26 −6
src/backend/executor/execExprInterp.c modified +8 −6

Discussion