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Peter Geoghegan 3c3b8a4b26 Truncate line pointer array during VACUUM.
Teach VACUUM to truncate the line pointer array of each heap page when a
contiguous group of LP_UNUSED line pointers appear at the end of the
array -- these unused and unreferenced items are excluded.  This process
occurs during VACUUM's second pass over the heap, right after LP_DEAD
line pointers on the page (those encountered/pruned during the first
pass) are marked LP_UNUSED.

Truncation avoids line pointer bloat with certain workloads,
particularly those involving continual range DELETEs and bulk INSERTs
against the same table.

Also harden heapam code to check for an out-of-range page offset number
in places where we weren't already doing so.

Author: Matthias van de Meent <boekewurm+postgres@gmail.com>
Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Masahiko Sawada <sawada.mshk@gmail.com>
Reviewed-By: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/CAEze2WjgaQc55Y5f5CQd3L=eS5CZcff2Obxp=O6pto8-f0hC4w@mail.gmail.com
Discussion: https://postgr.es/m/CAH2-Wzn6a64PJM1Ggzm=uvx2otsopJMhFQj_g1rAj4GWr3ZSzw@mail.gmail.com
2021-04-07 08:47:15 -07:00
config Update copyright for 2021 2021-01-02 13:06:25 -05:00
contrib libpq: Set Server Name Indication (SNI) for SSL connections 2021-04-07 15:11:41 +02:00
doc libpq: Set Server Name Indication (SNI) for SSL connections 2021-04-07 15:11:41 +02:00
src Truncate line pointer array during VACUUM. 2021-04-07 08:47:15 -07:00
.dir-locals.el Make Emacs perl-mode indent more like perltidy. 2019-01-13 11:32:31 -08:00
.editorconfig Add .editorconfig 2019-12-18 09:13:13 +01:00
.gitattributes gitattributes: Add new file 2019-11-12 08:13:55 +01:00
.gitignore Support for optimizing and emitting code in LLVM JIT provider. 2018-03-22 11:05:22 -07:00
aclocal.m4 Remove configure-time probe for DocBook DTD. 2020-11-30 15:24:13 -05:00
configure Refactor HMAC implementations 2021-04-03 17:30:49 +09:00
configure.ac Refactor HMAC implementations 2021-04-03 17:30:49 +09:00
COPYRIGHT Update copyright for 2021 2021-01-02 13:06:25 -05:00
GNUmakefile.in Make install-tests target work with vpath builds 2020-05-31 18:33:00 -04:00
HISTORY Canonicalize some URLs 2020-02-10 20:47:50 +01:00
Makefile Don't unset MAKEFLAGS in non-GNU Makefile. 2019-06-25 09:36:21 +12:00
README Canonicalize some URLs 2020-02-10 20:47:50 +01:00
README.git Canonicalize some URLs 2020-02-10 20:47:50 +01:00

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.

PostgreSQL has many language interfaces, many of which are listed here:

	https://www.postgresql.org/download/

See the file INSTALL for instructions on how to build and install
PostgreSQL.  That file also lists supported operating systems and
hardware platforms and contains information regarding any other
software packages that are required to build or run the PostgreSQL
system.  Copyright and license information can be found in the
file COPYRIGHT.  A comprehensive documentation set is included in this
distribution; it can be read as described in the installation
instructions.

The latest version of this software may be obtained at
https://www.postgresql.org/download/.  For more information look at our
web site located at https://www.postgresql.org/.