If there aren't many bytes to process, the function call overhead of the optimized implementation isn't worth taking, so instead we inline a loop that consults pg_number_of_ones in that case. If there are many bytes to process, we accept the function call overhead because the optimized versions are likely to be faster. The threshold at which we use the optimized implementation is set to the smallest amount of data required to use special popcount instructions. Reviewed-by: Alvaro Herrera, Tom Lane Discussion: https://postgr.es/m/20240402155301.GA2750455%40nathanxps13
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/.