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Andres Freund a97bbe1f1d Reduce branches in heapgetpage()'s per-tuple loop
Until now, heapgetpage()'s loop over all tuples performed some conditional
checks for each tuple, even though condition did not change across the loop.

This commit fixes that by moving the loop into an inline function. By calling
it with different constant arguments, the compiler can generate an optimized
loop for the different conditions, at the price of two per-page checks.

For cases of all-visible tables and an isolation level other than
serializable, speedups of up to 25% have been measured.

Reviewed-by: John Naylor <johncnaylorls@gmail.com>
Reviewed-by: Zhang Mingli <zmlpostgres@gmail.com>
Tested-by: Quan Zongliang <quanzongliang@yeah.net>
Discussion: https://postgr.es/m/20230716015656.xjvemfbp5fysjiea@awork3.anarazel.de
Discussion: https://postgr.es/m/2ef7ff1b-3d18-2283-61b1-bbd25fc6c7ce@yeah.net
2024-04-06 23:52:26 -07:00
config Optimize pg_popcount() with AVX-512 instructions. 2024-04-06 21:56:23 -05:00
contrib Make libpqsrv_cancel's return const char *, not char * 2024-04-05 18:23:10 +02:00
doc Support retrieval of results in chunks with libpq. 2024-04-06 20:45:11 -04:00
src Reduce branches in heapgetpage()'s per-tuple loop 2024-04-06 23:52:26 -07:00
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HISTORY Canonicalize some URLs 2020-02-10 20:47:50 +01:00
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README.md Revise the style of a paragraph in README.md. 2024-03-21 10:16:41 -05:00
aclocal.m4 autoconf: Move export_dynamic determination to configure 2022-12-06 18:55:28 -08:00
configure Optimize pg_popcount() with AVX-512 instructions. 2024-04-06 21:56:23 -05:00
configure.ac Optimize pg_popcount() with AVX-512 instructions. 2024-04-06 21:56:23 -05:00
meson.build Optimize pg_popcount() with AVX-512 instructions. 2024-04-06 21:56:23 -05:00
meson_options.txt Add backend support for injection points 2024-01-22 10:15:50 +09:00

README.md

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/.