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Andres Freund 00d1e02be2 hio: Use ExtendBufferedRelBy() to extend tables more efficiently 
While we already had some form of bulk extension for relations, it was fairly
limited. It only amortized the cost of acquiring the extension lock, the
relation itself was still extended one-by-one. Bulk extension was also solely
triggered by contention, not by the amount of data inserted.

To address this, use ExtendBufferedRelBy(), introduced in 31966b151e, to
extend the relation. We try to extend the relation by multiple blocks in two
situations:

1) The caller tells RelationGetBufferForTuple() that it will need multiple
   pages. For now that's only used by heap_multi_insert(), see commit FIXME.

2) If there is contention on the extension lock, use the number of waiters for
   the lock as a multiplier for the number of blocks to extend by. This is
   similar to what we already did. Previously we additionally multiplied the
   numbers of waiters by 20, but with the new relation extension
   infrastructure I could not see a benefit in doing so.

Using the freespacemap to provide empty pages can cause significant
contention, and adds measurable overhead, even if there is no contention. To
reduce that, remember the blocks the relation was extended by in the
BulkInsertState, in the extending backend. In case 1) from above, the blocks
the extending backend needs are not entered into the FSM, as we know that we
will need those blocks.

One complication with using the FSM to record empty pages, is that we need to
insert blocks into the FSM, when we already hold a buffer content lock. To
avoid doing IO while holding a content lock, release the content lock before
recording free space. Currently that opens a small window in which another
backend could fill the block, if a concurrent VACUUM records the free
space. If that happens, we retry, similar to the already existing case when
otherBuffer is provided. In the future it might be worth closing the race by
preventing VACUUM from recording the space in newly extended pages.

This change provides very significant wins (3x at 16 clients, on my
workstation) for concurrent COPY into a single relation. Even single threaded
COPY is measurably faster, primarily due to not dirtying pages while
extending, if supported by the operating system (see commit 4d330a61bb). Even
single-row INSERTs benefit, although to a much smaller degree, as the relation
extension lock rarely is the primary bottleneck.

Reviewed-by: Melanie Plageman <melanieplageman@gmail.com>
Discussion: https://postgr.es/m/20221029025420.eplyow6k7tgu6he3@awork3.anarazel.de
 		2023-04-06 16:53:17 -07:00
config autoconf: Move export_dynamic determination to configure 2022-12-06 18:55:28 -08:00
contrib postgres_fdw: Add support for parallel abort. 2023-04-06 17:30:00 +09:00
doc Add VACUUM/ANALYZE BUFFER_USAGE_LIMIT option 2023-04-07 11:40:31 +12:00
src hio: Use ExtendBufferedRelBy() to extend tables more efficiently 2023-04-06 16:53:17 -07:00
.cirrus.yml Allow to use system CA pool for certificate verification 2023-04-05 23:22:17 +02:00
.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 b6dfee28 to .git-blame-ignore-revs 2023-03-09 19:26:03 +09:00
.gitattributes gitattributes: Ignore imported pg_bsd_indent code for whitespace checks 2023-02-22 09:00:28 +01:00
.gitignore Update top-level .gitignore. 2022-12-04 15:23:00 -05:00
COPYRIGHT Update copyright for 2023 2023-01-02 15:00:37 -05:00
GNUmakefile.in Integrate pg_bsd_indent into our build/test infrastructure. 2023-02-12 12:22:21 -05:00
HISTORY Canonicalize some URLs 2020-02-10 20:47:50 +01:00
Makefile Dynamically find correct installation docs in Makefile. 2022-01-19 14:48:25 +01:00
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 autoconf: Move export_dynamic determination to configure 2022-12-06 18:55:28 -08:00
configure libpq: Add sslcertmode option to control client certificates 2023-03-24 13:34:26 +09:00
configure.ac libpq: Add sslcertmode option to control client certificates 2023-03-24 13:34:26 +09:00
meson.build meson: add docs, docs_pdf options 2023-04-04 21:29:39 -07:00
meson_options.txt meson: docs: Allow configuring simple/website style 2023-04-04 21:31:27 -07:00

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/.