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We break ROW(...) IS [NOT] NULL into separate tests on its component fields. During this breakdown, we can improve efficiency by utilizing expr_is_nonnullable() to detect fields that are provably non-nullable. If a component field is proven non-nullable, it affects the outcome based on the test type. For an IS NULL test, a single non-nullable field refutes the whole NullTest, reducing it to constant FALSE. For an IS NOT NULL test, the check for that specific field is guaranteed to succeed, so we can discard it from the list of component tests. This extends the existing optimization logic, which previously only handled Const fields, to support any expression that can be proven non-nullable. In passing, update the existing constant folding of NullTests to use expr_is_nonnullable() instead of var_is_nonnullable(), enabling it to benefit from future improvements to that function. Author: Richard Guo <guofenglinux@gmail.com> Reviewed-by: Tender Wang <tndrwang@gmail.com> Reviewed-by: Dagfinn Ilmari Mannsåker <ilmari@ilmari.org> Reviewed-by: David Rowley <dgrowleyml@gmail.com> Reviewed-by: Matheus Alcantara <matheusssilv97@gmail.com> Discussion: https://postgr.es/m/CAMbWs49UhPBjm+NRpxerjaeuFKyUZJ_AjM3NBcSYK2JgZ6VTEQ@mail.gmail.com
PostgreSQL Database Management System
This directory contains the source code distribution of the PostgreSQL database management system.
PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.
Copyright and license information can be found in the file COPYRIGHT.
General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/installation.html.
The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.