postgres/contrib
Andres Freund 2c78940527 bufmgr: Remove freelist, always use clock-sweep
This set of changes removes the list of available buffers and instead simply
uses the clock-sweep algorithm to find and return an available buffer.  This
also removes the have_free_buffer() function and simply caps the
pg_autoprewarm process to at most NBuffers.

While on the surface this appears to be removing an optimization it is in fact
eliminating code that induces overhead in the form of synchronization that is
problematic for multi-core systems.

The main reason for removing the freelist, however, is not the moderate
improvement in scalability, but that having the freelist would require
dedicated complexity in several upcoming patches. As we have not been able to
find a case benefiting from the freelist...

Author: Greg Burd <greg@burd.me>
Reviewed-by: Tomas Vondra <tomas@vondra.me>
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/70C6A5B5-2A20-4D0B-BC73-EB09DD62D61C@getmailspring.com
2025-09-05 12:25:59 -04:00
..
amcheck Remove unneeded casts of BufferGetPage() result 2025-08-29 07:18:29 +02:00
auth_delay Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
auto_explain Allow resetting unknown custom GUCs with reserved prefixes. 2025-08-01 16:52:11 -05:00
basebackup_to_shell meson: Increase minimum version to 0.57.2 2025-07-02 11:14:53 +02:00
basic_archive Remove translation marker from libpq-be-fe-helpers.h. 2025-07-22 22:08:36 +09:00
bloom Remove unneeded casts of BufferGetPage() result 2025-08-29 07:18:29 +02:00
bool_plperl Fix erroneous construction of functions' dependencies on transforms. 2025-04-07 13:31:37 -04:00
btree_gin Add more cross-type comparisons to contrib/btree_gin. 2025-07-03 16:30:38 -04:00
btree_gist Avoid including tableam.h and xlogreader.h in nbtree.h 2025-08-14 17:48:46 +02:00
citext Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
cube Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
dblink postgres_fdw and dblink should check if backend has MyProcPort 2025-08-08 19:34:31 +02:00
dict_int Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
dict_xsyn Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
earthdistance Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
file_fdw Disallow "=" in names of reloptions and foreign-data options. 2025-06-02 15:22:44 -04:00
fuzzystrmatch Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
hstore Fix varatt versus Datum type confusions 2025-08-05 12:11:36 +02:00
hstore_plperl Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
hstore_plpython Remove circular #include's between plpython.h and plpy_util.h. 2025-04-27 11:43:02 -04:00
intagg Update copyright for 2025 2025-01-01 11:21:55 -05:00
intarray Add missing Datum conversions 2025-08-08 22:06:57 +02:00
isn Use pg_ascii_tolower()/pg_ascii_toupper() where appropriate. 2025-07-01 07:24:23 -07:00
jsonb_plperl Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
jsonb_plpython Remove circular #include's between plpython.h and plpy_util.h. 2025-04-27 11:43:02 -04:00
lo Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
ltree Mop-up for Datum conversion cleanups. 2025-08-08 18:44:57 -04:00
ltree_plpython Remove circular #include's between plpython.h and plpy_util.h. 2025-04-27 11:43:02 -04:00
oid2name Update copyright for 2025 2025-01-01 11:21:55 -05:00
pageinspect Add missing Datum conversions 2025-08-08 22:06:57 +02:00
passwordcheck Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
pg_buffercache Add CHECK_FOR_INTERRUPTS in contrib/pg_buffercache functions. 2025-08-19 12:11:42 -07:00
pg_freespacemap Prevent assertion failure in contrib/pg_freespacemap. 2025-03-27 13:20:23 -04:00
pg_logicalinspect Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
pg_overexplain Revert support for improved tracking of nested queries 2025-06-12 10:08:55 +09:00
pg_prewarm bufmgr: Remove freelist, always use clock-sweep 2025-09-05 12:25:59 -04:00
pg_stat_statements Change dynahash.c and hsearch.h to use int64 instead of long 2025-08-22 11:59:02 +09:00
pg_surgery Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
pg_trgm Put "excludeOnly" GIN scan keys at the end of the scankey array. 2025-08-26 12:08:57 -04:00
pg_visibility read_stream: Introduce and use optional batchmode support 2025-03-30 18:36:41 -04:00
pg_walinspect Standardize LSN formatting by zero padding 2025-07-07 13:57:43 +02:00
pgcrypto Fix incorrect format placeholder 2025-04-08 19:12:03 +02:00
pgrowlocks Add missing Datum conversions 2025-08-08 22:06:57 +02:00
pgstattuple Remove unneeded casts of BufferGetPage() result 2025-08-29 07:18:29 +02:00
postgres_fdw postgres_fdw: Use psql variables for connection parameters 2025-09-01 09:02:03 +09:00
seg Add missing Datum conversions 2025-08-08 22:06:57 +02:00
sepgsql Avoid including commands/dbcommands.h in so many places 2025-08-28 12:39:04 +02:00
spi Use pg_ascii_tolower()/pg_ascii_toupper() where appropriate. 2025-07-01 07:24:23 -07:00
sslinfo Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
start-scripts Remove gratuitous references to postmaster program 2023-01-26 10:48:32 +01:00
tablefunc Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
tcn Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
test_decoding Fix varatt versus Datum type confusions 2025-08-05 12:11:36 +02:00
tsm_system_rows Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
tsm_system_time Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
unaccent Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
uuid-ossp Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
vacuumlo Update copyright for 2025 2025-01-01 11:21:55 -05:00
xml2 Fix up misuse of "volatile" in contrib/xml2. 2025-07-08 17:00:34 -04:00
contrib-global.mk Respect TEMP_CONFIG when pg_regress_check and friends are called 2016-02-27 12:28:21 -05:00
Makefile pg_overexplain: Additional EXPLAIN options for debugging. 2025-03-26 13:52:21 -04:00
meson.build pg_overexplain: Additional EXPLAIN options for debugging. 2025-03-26 13:52:21 -04:00
README

The PostgreSQL contrib tree
---------------------------

This subtree contains porting tools, analysis utilities, and plug-in
features that are not part of the core PostgreSQL system, mainly
because they address a limited audience or are too experimental to be
part of the main source tree.  This does not preclude their
usefulness.

User documentation for each module appears in the main SGML
documentation.

When building from the source distribution, these modules are not
built automatically, unless you build the "world" target.  You can
also build and install them all by running "make all" and "make
install" in this directory; or to build and install just one selected
module, do the same in that module's subdirectory.

Some directories supply new user-defined functions, operators, or
types.  To make use of one of these modules, after you have installed
the code you need to register the new SQL objects in the database
system by executing a CREATE EXTENSION command.  In a fresh database,
you can simply do

    CREATE EXTENSION module_name;

See the PostgreSQL documentation for more information about this
procedure.