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ExecEvalHashedScalarArrayOp(), when using a strict equality function, performs a short-circuit when looking up NULL values. When the function is non-strict, the code incorrectly looked up the hash table for a zero-valued Datum, which could have resulted in an accidental true return if the hash table contained zero valued Datum, or could result in a crash for non-byval types. Here we fix this by adding an extra step when we build the hash table to check what the result of a NULL lookup would be. This requires looping over the array and checking what the non-hashed version of the code would do. We cache the results of that in the expression so that we can reuse the result any time we're asked to search for a NULL value. It's important to note that non-strict equality functions are free to treat any NULL value as equal to any non-NULL value. For example, someone may wish to design a type that treats an empty string and NULL as equal. All built-in types have strict equality functions, so this could affect custom / user-defined types. Author: Chengpeng Yan <chengpeng_yan@outlook.com> Author: David Rowley <dgrowleyml@gmail.com> Reviewed-by: ChangAo Chen <cca5507@qq.com> Discussion: https://postgr.es/m/A16187AE-2359-4265-9F5E-71D015EC2B2D@outlook.com Backpatch-through: 14
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/17/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/17/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/.