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Peter Geoghegan 4f8d9d1217 vacuumlazy.c: Rename dead_tuples to dead_items. 
Commit 8523492d simplified what it meant for an item to be considered
"dead" to VACUUM: TIDs collected in memory (in preparation for index
vacuuming) must always come from LP_DEAD stub line pointers in heap
pages, found following pruning.  This formalized the idea that index
vacuuming (and heap vacuuming) are optional processes.  Unlike pruning,
they can be delayed indefinitely, without any risk of that violating
fundamental invariants.  For example, leaving LP_DEAD items behind
clearly won't add to the risk of transaction ID wraparound.  You can't
have transaction ID wraparound without transaction IDs.  Renaming
anything that references DEAD tuples (tuples with storage) reinforces
all this.

Code outside vacuumlazy.c continues to fudge the distinction between
dead/deleted tuples, and LP_DEAD items.  This is necessary because
autovacuum scheduling is still mostly driven by "dead items/tuples"
statistics.  In the future we may find it useful to replace this model
with something more sophisticated, as a step towards teaching autovacuum
to perform more frequent vacuuming that targeting individual indexes
that happen to be more prone to becoming bloated through version churn.

In passing, simplify some function signatures that deal with VACUUM's
dead_items array.

Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Masahiko Sawada <sawada.mshk@gmail.com>
Discussion: https://postgr.es/m/CAH2-WzktGBg4si6DEdmq3q6SoXSDqNi6MtmB8CmmTmvhsxDTLA@mail.gmail.com
 		2021-11-29 09:58:01 -08:00
config Pacify perlcritic. 2021-11-22 15:57:31 -05:00
contrib Replace random(), pg_erand48(), etc with a better PRNG API and algorithm. 2021-11-28 21:33:07 -05:00
doc Doc: improve documentation about ORDER BY in matviews. 2021-11-29 12:13:12 -05:00
src vacuumlazy.c: Rename dead_tuples to dead_items. 2021-11-29 09:58:01 -08:00
.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
.git-blame-ignore-revs Add another old commit to git-blame-ignore-revs. 2021-11-03 17:34:19 -07:00
.gitattributes gitattributes: Add new entry to silence whitespace error 2021-06-05 07:57:31 +02:00
.gitignore Support for optimizing and emitting code in LLVM JIT provider. 2018-03-22 11:05:22 -07:00
COPYRIGHT Update copyright for 2021 2021-01-02 13:06:25 -05:00
GNUmakefile.in add missing tag from commit b8c4261e5e 2021-07-01 15:47:46 -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
aclocal.m4 Probe $PROVE not $PERL while checking for modules needed by TAP tests. 2021-11-22 12:54:52 -05:00
configure Replace random(), pg_erand48(), etc with a better PRNG API and algorithm. 2021-11-28 21:33:07 -05:00
configure.ac Replace random(), pg_erand48(), etc with a better PRNG API and algorithm. 2021-11-28 21:33:07 -05:00

README 

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/.