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Mirror of the official PostgreSQL GIT repository. Note that this is just a *mirror* - we don't work with pull requests on github. To contribute, please see https://wiki.postgresql.org/wiki/Submitting_a_Patch
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David Rowley 0f5738202b Use ExprStates for hashing in GROUP BY and SubPlans 
This speeds up obtaining hash values for GROUP BY and hashed SubPlans by
using the ExprState support for hashing, thus allowing JIT compilation for
obtaining hash values for these operations.

This, even without JIT compilation, has been shown to improve Hash
Aggregate performance in some cases by around 15% and hashed NOT IN
queries in one case by over 30%, however, real-world cases are likely to
see smaller gains as the test cases used were purposefully designed to
have high hashing overheads by keeping the hash table small to prevent
additional memory overheads that would be a factor when working with large
hash tables.

In passing, fix a hypothetical bug in ExecBuildHash32Expr() so that the
initial value is stored directly in the ExprState's result field if
there are no expressions to hash.  None of the current users of this
function use an initial value, so the bug is only hypothetical.

Reviewed-by: Andrei Lepikhov <lepihov@gmail.com>
Discussion: https://postgr.es/m/CAApHDvpYSO3kc9UryMevWqthTBrxgfd9djiAjKHMPUSQeX9vdQ@mail.gmail.com
2024-12-11 13:47:16 +13:00
.github Add CODE_OF_CONDUCT.md, CONTRIBUTING.md, and SECURITY.md. 2024-07-02 13:03:58 -05:00
config Use <stdint.h> and <inttypes.h> for c.h integers. 2024-12-04 15:05:38 +13:00
contrib Simplify executor's determination of whether to use parallelism. 2024-12-09 14:38:19 -05:00
doc Use in-place updates for pg_restore_relation_stats(). 2024-12-10 16:30:37 -08:00
src Use ExprStates for hashing in GROUP BY and SubPlans 2024-12-11 13:47:16 +13:00
.cirrus.star Remove duplicate words in docs and code comments. 2023-10-09 09:18:47 +05:30
.cirrus.tasks.yml ci: Fix cached MacPorts installation management 2024-11-27 11:51:54 -05:00
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configure Use <stdint.h> and <inttypes.h> for c.h integers. 2024-12-04 15:05:38 +13:00
configure.ac Use <stdint.h> and <inttypes.h> for c.h integers. 2024-12-04 15:05:38 +13:00
COPYRIGHT Update copyright for 2024 2024-01-03 20:49:05 -05:00
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Makefile Remove AIX support 2024-02-28 15:17:23 +04:00
meson_options.txt Make PG_TEST_EXTRA env var override the "meson setup" option 2024-11-04 14:09:25 +02:00
meson.build Use <stdint.h> and <inttypes.h> for c.h integers. 2024-12-04 15:05:38 +13:00
README.md Revise the style of a paragraph in README.md. 2024-03-21 10:16:41 -05:00

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/.