87f81a5563
adf97c156 gave ExprStates the ability to hash expressions and return a single hash value. That commit supports seeding the hash value with an initial value to have that blended into the final hash value. Here we fix a hypothetical bug where if there are zero expressions to hash, the initial value is stored in the wrong location. The existing code stored the initial value in an intermediate location expecting that when the expressions were hashed that those steps would store the final hash value in the ExprState.resvalue field. However, that wouldn't happen when there are zero expressions to hash. The correct thing to do instead is to have a special case for zero expressions and when we hit that case, store the initial value directly in the ExprState.resvalue. The reason that this is a hypothetical bug is that no code currently calls ExecBuildHash32Expr passing a non-zero initial value. Discussion: https://postgr.es/m/CAApHDvpMAL_zxbMRr1LOex3O7Y7R7ZN2i8iUFLQhqQiJMAg3qw@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/.