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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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Peter Geoghegan 21a152b37f Improve nbtree skip scan primitive scan scheduling. 
Don't allow nbtree scans with skip arrays to end any primitive scan on
its first leaf page without giving some consideration to how many times
the scan's arrays advanced while changing at least one skip array
(though continue not caring about the number of array advancements that
only affected SAOP arrays, even during skip scans with SAOP arrays).
Now when a scan performs more than 3 such array advancements in the
course of reading a single leaf page, it is taken as a signal that the
next page is unlikely to be skippable.  We'll therefore continue the
ongoing primitive index scan, at least until we can perform a recheck
against the next page's finaltup.

Testing has shown that this new heuristic occasionally makes all the
difference with skip scans that were expected to rely on the "passed
first page" heuristic added by commit 9a2e2a28.  Without it, there is a
remaining risk that certain kinds of skip scans will never quite manage
to clear the initial hurdle of performing a primitive scan that lasts
beyond its first leaf page (or that such a skip scan will only clear
that initial hurdle when it has already wasted noticeably-many cycles
due to inefficient primitive scan scheduling).

Follow-up to commits 92fe23d9 and 9a2e2a28.

Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Matthias van de Meent <boekewurm+postgres@gmail.com>
Discussion: https://postgr.es/m/CAH2-Wz=RVdG3zWytFWBsyW7fWH7zveFvTHed5JKEsuTT0RCO_A@mail.gmail.com
2025-04-04 13:58:05 -04:00
.github Add CODE_OF_CONDUCT.md, CONTRIBUTING.md, and SECURITY.md. 2024-07-02 13:03:58 -05:00
config Optimize popcount functions with ARM SVE intrinsics. 2025-03-28 16:20:20 -05:00
contrib Fix autoprewarm neglect of tablespaces 2025-04-04 11:34:06 -04:00
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src Improve nbtree skip scan primitive scan scheduling. 2025-04-04 13:58:05 -04:00
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meson_options.txt aio: Add liburing dependency 2025-03-26 19:45:32 -04:00
meson.build libpq: Add support for dumping SSL key material to file 2025-04-03 13:16:43 +02:00
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/.