c95cd2991f
ScalarArrayOpExpr used for either NOT IN or <>/= ALL, when the array contains a NULL constant, will never evaluate to true. Here we add an explicit short-circuit in scalararraysel() to account for this and return 0.0 rows when we see that a NULL exists. When the array is a constant, we can very quickly see if there are any NULL values and return early before going to much effort in scalararraysel(). For non-const arrays, we short-circuit after finding the first NULL and forego selectivity estimations of any remaining elements. In the future, it might be better to do something for this case in constant folding. We would need to be careful to only do this for strict operators on expressions located in places that don't care about distinguishing false from NULL returns. i.e. EXPRKIND_QUAL expressions. Doing that requires a bit more thought and effort, so here we just fix some needlessly slow selectivity estimations for ScalarArrayOpExpr containing many array elements and at least one NULL. Author: Ilia Evdokimov <ilya.evdokimov@tantorlabs.com> Reviewed-by: David Geier <geidav.pg@gmail.com> Reviewed-by: Zsolt Parragi <zsolt.parragi@percona.com> Reviewed-by: David Rowley <dgrowleyml@gmail.com> Discussion: https://postgr.es/m/eaa2598c-5356-4e1e-9ec3-5fd6eb1cd704@tantorlabs.com |
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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/.