Commit Graph

14295 Commits

Author SHA1 Message Date
Bruce Momjian 64084d6857 doc: update PG 12 release notes, v2
Adjustments requested by reviewers.

Reported-by: Amit Kapila, Thomas Munro, Andrew Gierth, Amit Langote, Oleg Bartunov, Michael Paquier, Alvaro Herrera, Tatsuo Ishii

Discussion: https://postgr.es/m/20190506233029.ozwged67i7s4qd6c@momjian.us
2019-05-09 16:44:27 -04:00
Etsuro Fujita a0be05bab0 Doc: Update FDW documentation about GetForeignUpperPaths().
In commit d50d172e51, which added support for LIMIT/OFFSET pushdown in
postgres_fdw, a new struct was introduced as the extra parameter of
GetForeignUpperPaths() set for UPPERREL_FINAL, but I forgot to update
the documentation to mention that.

Author: Etsuro Fujita
Discussion: https://postgr.es/m/CAPmGK17uSXQDe31oRb-z1nYyT6vVzkstZkA3_Wbq38U92b9BmQ%40mail.gmail.com
2019-05-09 19:50:15 +09:00
Peter Eisentraut 02daece4ab Fix grammar in error message 2019-05-09 09:16:59 +02:00
Fujii Masao df631ebc73 Fix documentation for the privileges required for replication functions.
Previously it's documented that use of replication functions is
restricted to superusers. This is true for the functions which
use replication origin, but not for pg_logicl_emit_message() and
functions which use replication slot. For example, not only
superusers but also users with REPLICATION privilege is allowed
to use the functions for replication slot. This commit fixes
the documentation for the privileges required for those replication
functions.

Back-patch to 9.4 (all supported versions).

Author: Matsumura Ryo
Discussion: https://postgr.es/m/03040DFF97E6E54E88D3BFEE5F5480F74ABA6E16@G01JPEXMBYT04
2019-05-09 01:35:13 +09:00
Thomas Munro 098344be66 Fix copy-and-paste mistakes in documentation.
Reported-by: Vik Fearing
2019-05-08 21:16:36 +12:00
Alexander Korotkov 53ae0b16d6 Remove word "singleton" out of jsonpath docs
Word "singleton" is hard for user understanding, especially taking into account
there is only one place it's used in the docs and there is even no definition.
Use more evident wording instead.

Discussion: https://postgr.es/m/23737.1556550645%40sss.pgh.pa.us
2019-05-08 01:02:59 +03:00
Fujii Masao b84dbc8eb8 Add TRUNCATE parameter to VACUUM.
This commit adds new parameter to VACUUM command, TRUNCATE,
which specifies that VACUUM should attempt to truncate off
any empty pages at the end of the table and allow the disk space
for the truncated pages to be returned to the operating system.

This parameter, if specified, overrides the vacuum_truncate
reloption. If neither the reloption nor the VACUUM option is
used, the default is true, as before.

Author: Fujii Masao
Reviewed-by: Julien Rouhaud, Masahiko Sawada
Discussion: https://postgr.es/m/CAD21AoD+qtrSDL=GSma4Wd3kLYLeRC0hPna-YAdkDeV4z156vg@mail.gmail.com
2019-05-08 02:10:33 +09:00
Peter Eisentraut b753bc0c84 doc: Generate keywords table automatically
The SQL keywords table in the documentation had until now been
generated by some ad hoc scripting outside the source tree once for
each major release.  This changes it to an automated process.

We have the PostgreSQL keywords available in a parseable format in
parser/kwlist.h.  For the relevant SQL standard versions, keep the
keyword lists in new text files.  A new script
generate-keywords-table.pl pulls it all together and produces a
DocBook table.

The final output in the documentation should be identical after this
change.

Discussion: https://www.postgresql.org/message-id/flat/07daeadd-8c82-0d95-5e19-e350502cb749%402ndquadrant.com
2019-05-07 15:29:39 +02:00
Amit Kapila 7db0cde6b5 Revert "Avoid the creation of the free space map for small heap relations".
This feature was using a process local map to track the first few blocks
in the relation.  The map was reset each time we get the block with enough
freespace.  It was discussed that it would be better to track this map on
a per-relation basis in relcache and then invalidate the same whenever
vacuum frees up some space in the page or when FSM is created.  The new
design would be better both in terms of API design and performance.

List of commits reverted, in reverse chronological order:

06c8a5090e  Improve code comments in b0eaa4c51b.
13e8643bfc  During pg_upgrade, conditionally skip transfer of FSMs.
6f918159a9  Add more tests for FSM.
9c32e4c350  Clear the local map when not used.
29d108cdec  Update the documentation for FSM behavior..
08ecdfe7e5  Make FSM test portable.
b0eaa4c51b  Avoid creation of the free space map for small heap relations.

Discussion: https://postgr.es/m/20190416180452.3pm6uegx54iitbt5@alap3.anarazel.de
2019-05-07 09:30:24 +05:30
Bruce Momjian bdf595adbc docs: fist draft version of the PG 12 release notes
Still needs text markup, links, word wrap, and indenting.
2019-05-06 19:02:34 -04:00
Tom Lane 8309eae499 Doc: remove obsolete comment about per-branch documentation.
I should have removed this in a0b762626, but forgot.
2019-05-03 12:32:06 -04:00
Bruce Momjian 26950273dc doc: clarify behavior of pg_upgrade's clone mode
Be more precise about the benefits of using clone mode.
2019-05-01 09:09:28 -04:00
Andres Freund b06a354e38 docs: Fix small copy & paste mistake.
Author: Justin Pryzby
Discussion: https://postgr.es/m/20190418005115.r4mat75wvlski3ij@alap3.anarazel.de
2019-04-30 16:20:07 -07:00
Tom Lane e03ff73969 Clean up handling of constraint_exclusion and enable_partition_pruning.
The interaction of these parameters was a bit confused/confusing,
and in fact v11 entirely misses the opportunity to apply partition
constraints when a partition is accessed directly (rather than
indirectly from its parent).

In HEAD, establish the principle that enable_partition_pruning controls
partition pruning and nothing else.  When accessing a partition via its
parent, we do partition pruning (if enabled by enable_partition_pruning)
and then there is no need to consider partition constraints in the
constraint_exclusion logic.  When accessing a partition directly, its
partition constraints are applied by the constraint_exclusion logic,
only if constraint_exclusion = on.

In v11, we can't have such a clean division of these GUCs' effects,
partly because we don't want to break compatibility too much in a
released branch, and partly because the clean coding requires
inheritance_planner to have applied partition pruning to a partitioned
target table, which it doesn't in v11.  However, we can tweak things
enough to cover the missed case, which seems like a good idea since
it's potentially a performance regression from v10.  This patch keeps
v11's previous behavior in which enable_partition_pruning overrides
constraint_exclusion for an inherited target table, though.

In HEAD, also teach relation_excluded_by_constraints that it's okay to use
inheritable constraints when trying to prune a traditional inheritance
tree.  This might not be thought worthy of effort given that that feature
is semi-deprecated now, but we have enough infrastructure that it only
takes a couple more lines of code to do it correctly.

Amit Langote and Tom Lane

Discussion: https://postgr.es/m/9813f079-f16b-61c8-9ab7-4363cab28d80@lab.ntt.co.jp
Discussion: https://postgr.es/m/29069.1555970894@sss.pgh.pa.us
2019-04-30 15:03:50 -04:00
Bruce Momjian ad23adc5a1 doc: improve PG 12 to_timestamp()/to_date() wording 2019-04-30 14:06:57 -04:00
Bruce Momjian 3454738625 doc: move "only" to a more appropriate place in the sentence 2019-04-30 13:44:31 -04:00
Michael Paquier ac86237603 Fix more typos and inconsistencies in documentation
This fixes a couple of grammar mistakes, typos and inconsistencies in
the documentation.  Particularly, the configuration parsing allows only
"kB" to mean kilobyte but there were references in the docs to "KB".
Some instances of the latter are still in the code comments.  Some
parameter values were mentioned with "Minus-one", and using directly
"-1" with proper markups is more helpful to the reader.

Some of these have been pointed out by Justin, and some others are
things I bumped into.

Author: Justin Pryzby, Michael Paquier
Reviewed-by: Tom Lane
Discussion: https://postgr.es/m/20190330224333.GQ5815@telsasoft.com
2019-04-28 22:53:33 +09:00
Joe Conway 29046c44f3 Add viewBox attribute to storage page layout SVG image
Recently added SVG image for storage page layout lacks
a viewBox attribute which seems necessary to ensure propoer
rendering. Add it.

Author: Jonathan Katz
Discussion: https://postgr.es/m/ba31e0e1-4c9b-b309-70e8-8e7ac14fc87e%40postgresql.org
2019-04-27 11:36:51 -04:00
Joe Conway 7dc78d8ef3 Add guidance on making documentation SVG images responsive
Recently added guidance on adding SVG images to the documentation
sources lacks advice on making the images responsive when rendered
in a variety of media types and viewports. Add some.

Patch by Jonathan Katz with some editorialization by me.

Author: Jonathan Katz
Discussion: https://postgr.es/m/6358ae6f-7191-a02b-e7b5-68050636ae71@postgresql.org
2019-04-27 11:12:52 -04:00
Joe Conway cf3ff97a15 Correct the URL pointing to PL/R
As pointed out by documentation comment, the URL for PL/R
needs to be updated to the correct current repository. Back-patch
to all supported branches.
2019-04-27 09:30:22 -04:00
Michael Paquier a967878414 Mention REINDEX CONCURRENTLY in documentation about index maintenance
The documentation includes a section about index maintenance and
reindexing, mentioning a set of steps based on CREATE INDEX CONCURRENTLY
and ALTER TABLE (for constraint dependencies) to emulate REINDEX
CONCURRENTLY.  Now that REINDEX CONCURRENTLY is supported, let's just
directly mention it instead.

Reported-by: Peter Geoghegan
Author: Michael Paquier
Reviewed-by: Peter Eisentraut, Tom Lane
Discussion: https://postgr.es/m/CAH2-WzmEL168t6w29aKrKXtpq9-apcmp0HC7K-fKt6ZgLXV6Dg@mail.gmail.com
2019-04-27 09:06:39 +09:00
Peter Eisentraut 686fef22fd Update key words table for version 12 2019-04-26 23:24:13 +02:00
Peter Eisentraut 60bbf0753e doc: Update section on NFS
The old section was ancient and didn't seem very helpful.  Here, we
add some concrete advice on particular mount options.

Reviewed-by: Joe Conway <mail@joeconway.com>
Discussion: https://www.postgresql.org/message-id/flat/e90f24bb-5423-6abb-58ec-501176eb4afc%402ndquadrant.com
2019-04-26 11:50:34 +02:00
Etsuro Fujita 90fca7a35a Add FDW documentation notes about insert and update tuple routing and COPY.
Author: Laurenz Albe and Etsuro Fujita
Reviewed-by: Laurenz Albe and Amit Langote
Backpatch-through: 11 where support for that by FDWs was added
Discussion: https://postgr.es/m/bf36a0288e8f31b4f2f40952e225bf892dc1ffc5.camel@cybertec.at
2019-04-26 18:10:05 +09:00
Alvaro Herrera 87259588d0 Fix tablespace inheritance for partitioned rels
Commit ca4103025d left a few loose ends.  The most important one
(broken pg_dump output) is already fixed by virtue of commit
3b23552ad8, but some things remained:

* When ALTER TABLE rewrites tables, the indexes must remain in the
  tablespace they were originally in.  This didn't work because
  index recreation during ALTER TABLE runs manufactured SQL (yuck),
  which runs afoul of default_tablespace in competition with the parent
  relation tablespace.  To fix, reset default_tablespace to the empty
  string temporarily, and add the TABLESPACE clause as appropriate.

* Setting a partitioned rel's tablespace to the database default is
  confusing; if it worked, it would direct the partitions to that
  tablespace regardless of default_tablespace.  But in reality it does
  not work, and making it work is a larger project.  Therefore, throw
  an error when this condition is detected, to alert the unwary.

Add some docs and tests, too.

Author: Álvaro Herrera
Discussion: https://postgr.es/m/CAKJS1f_1c260nOt_vBJ067AZ3JXptXVRohDVMLEBmudX1YEx-A@mail.gmail.com
2019-04-25 10:31:32 -04:00
Etsuro Fujita 5c47049180 postgres_fdw: Fix incorrect handling of row movement for remote partitions.
Commit 3d956d9562 added support for update row movement in postgres_fdw.
This patch fixes the following issues introduced by that commit:

* When a remote partition chosen to insert routed rows into was also an
  UPDATE subplan target rel that would be updated later, the UPDATE that
  used a direct modification plan modified those routed rows incorrectly
  because those routed rows were visible to the later UPDATE command.
  The right fix for this would be to have some way in postgres_fdw in
  which the later UPDATE command ignores those routed rows, but it seems
  hard to do so with the current infrastructure.  For now throw an error
  in that case.

* When a remote partition chosen to insert routed rows into was also an
  UPDATE subplan target rel, fmstate created for the UPDATE that used a
  non-direct modification plan was mistakenly overridden by another
  fmstate created for inserting those routed rows into the partition.
  This caused 1) server crash when the partition would be updated later,
  and 2) resource leak when the partition had been already updated.  To
  avoid that, adjust the treatment of the fmstate for the inserting.  As
  for #1, since we would also have the incorrectness issue as mentioned
  above, error out in that case as well.

Update the docs to mention that postgres_fdw currently does not handle
the case where a remote partition chosen to insert a routed row into is
also an UPDATE subplan target rel that will be updated later.

Author: Amit Langote and Etsuro Fujita
Reviewed-by: Amit Langote
Backpatch-through: 11 where row movement in postgres_fdw was added
Discussion: https://postgr.es/m/21e7eaa4-0d4d-20c2-a1f7-c7e96f4ce440@lab.ntt.co.jp
2019-04-24 18:31:50 +09:00
Fujii Masao b804c1837b Fix documentation of pg_start_backup and pg_stop_backup functions.
This commit adds the description that "non-exclusive" pg_start_backup
and pg_stop_backup can be executed even during recovery. Previously
it was wrongly documented that those functions are not allowed to be
executed during recovery.

Back-patch to 9.6 where non-exclusive backup API was added.

Discussion: https://postgr.es/m/CAHGQGwEuAYrEX7Yhmf2MCrTK81HDkkg-JqsOUh8zw6+zYC5zzw@mail.gmail.com
2019-04-23 02:41:58 +09:00
Bruce Momjian bfbc150e39 docs: reorder collation regression test order in paragraph
Backpatch-through: 10
2019-04-20 11:18:43 -04:00
Stephen Frost eb882a1b71 GSSAPI: Improve documentation and tests
The GSSAPI encryption patch neglected to update the protocol
documentation to describe how to set up a GSSAPI encrypted connection
from a client to the server, so fix that by adding the appropriate
documentation to protocol.sgml.

The tests added for encryption support were overly long and couldn't be
run in parallel due to race conditions; this was largely because each
test was setting up its own KDC to perform the tests.  Instead, merge
the authentication tests and the encryption tests into the original
test, where we only create one KDC to run the tests with.  Also, have
the tests check what the server's opinion is of the connection and if it
was GSS authenticated or encrypted using the pg_stat_gssapi view.

In passing, fix the libpq label for GSSENC-Mode to be consistent with
the "PGGSSENCMODE" environment variable.

Missing protocol documentation pointed out by Michael Paquier.
Issues with the tests pointed out by Tom Lane and Peter Eisentraut.

Refactored tests and added documentation by me.

Reviewed by Robbie Harwood (protocol documentation) and Michael Paquier
(rework of the tests).
2019-04-19 21:22:22 -04:00
Michael Paquier 148266fa35 Fix collection of typos and grammar mistakes in docs and comments
Author: Justin Pryzby
Discussion: https://postgr.es/m/20190330224333.GQ5815@telsasoft.com
2019-04-19 16:57:40 +09:00
Michael Paquier bc540f9859 Clean up some documentation for log_statement_sample_rate
This was missing from 88bdbd3.

Author: Christoph Berg, Justin Pryzby
Discussion: https://postgr.es/m/20190403215938.GA26375@alvherre.pgsql
Discussion: https://postgr.es/m/20190330224333.GQ5815@telsasoft.com
2019-04-19 16:26:41 +09:00
Andres Freund 1cebfdee00 docs: correct typo-ed path to heapam_handler.c.
Reported-By: Michael Paquier, Michel Pelletier
Discussion:
   https://postgr.es/m/20190410025531.GA2728@paquier.xyz
   https://postgr.es/m/CACxu=v+u_QTeFqdajCHv3i4QmzV_63arVb57R19dSKtThdSLkQ@mail.gmail.com
2019-04-17 17:31:54 -07:00
Andres Freund f6b39171f3 docs: cleanup/remove/update references to OID column.
I (Andres) missed these in 578b229718.

Author: Justin Pryzby, editorialized a bit by Andres Freund
Reviewed-By: Daniel Verite, Andres Freund
Discussion: https://postgr.es/m/20190408002847.GA904@telsasoft.com
2019-04-17 17:22:56 -07:00
Alvaro Herrera 421a2c4832 Tie loose ends in psql's new \dP command
* Remove one unnecessary pg_class join in SQL command.  Not needed,
  because we use a regclass cast instead.

* Doc: refer to "partitioned relations" rather than specifically tables,
  since indexes are also displayed.

* Rename "On table" column to "Table", for consistency with \di.

Author: Justin Pryzby
Discussion: https://postgr.es/m/20190407212525.GB10080@telsasoft.com
2019-04-17 18:38:49 -04:00
Bruce Momjian 64bbe10399 docs: clarify pg_upgrade's recovery behavior
The previous paragraph trying to explain --check, --link, and no --link
modes and the various points of failure was too complex.  Instead, use
bullet lists and sublists.

Reported-by: Daniel Gustafsson

Discussion: https://postgr.es/m/qtqiv7hI87s_Xvz5ZXHCaH-1-_AZGpIDJowzlRjF3-AbCr3RhSNydM_JCuJ8DE4WZozrtxhIWmyYTbv0syKyfGB6cYMQitp9yN-NZMm-oAo=@yesql.se

Backpatch-through: 9.4
2019-04-17 18:01:02 -04:00
Magnus Hagander 252b707bc4 Return NULL for checksum failures if checksums are not enabled
Returning 0 could falsely indicate that there is no problem. NULL
correctly indicates that there is no information about potential
problems.

Also return 0 as numbackends instead of NULL for shared objects (as no
connection can be made to a shared object only).

Author: Julien Rouhaud <rjuju123@gmail.com>
Reviewed-by: Robert Treat <rob@xzilla.net>
2019-04-17 13:51:48 +02:00
Michael Paquier a6dcf9df4d Rework handling of invalid indexes with REINDEX CONCURRENTLY
Per discussion with others, allowing REINDEX INDEX CONCURRENTLY to work
for invalid indexes when working directly on them can have a lot of
value to unlock situations with invalid indexes without having to use a
dance involving DROP INDEX followed by an extra CREATE INDEX
CONCURRENTLY (which would not work for indexes with constraint
dependency anyway).  This also does not create extra bloat on the
relation involved as this works on individual indexes, so let's enable
it.

Note that REINDEX TABLE CONCURRENTLY still bypasses invalid indexes as
we don't want to bloat the number of indexes defined on a relation in
the event of multiple and successive failures of REINDEX CONCURRENTLY.

More regression tests are added to cover those behaviors, using an
invalid index created with CREATE INDEX CONCURRENTLY.

Reported-by: Dagfinn Ilmari Mannsåker, Álvaro Herrera
Author: Michael Paquier
Reviewed-by: Peter Eisentraut, Dagfinn Ilmari Mannsåker
Discussion: https://postgr.es/m/20190411134947.GA22043@alvherre.pgsql
2019-04-17 09:33:51 +09:00
Fujii Masao c8e0f6bbdb Add index terms for reloptions in documentation.
Author: Fujii Masao
Reviewed-By: Alvaro Herrera, Michael Paquier
Discussion: https://postgr.es/m/CAHGQGwHyKt9-xkibVguPzYqKgb_2tdw14Ub1XDTu08kyHMiTQA@mail.gmail.com
2019-04-16 23:16:20 +09:00
Peter Eisentraut e446cde16d Better scaling of images in HTML output
Turn on the previously disabled automatic scaling of images in HTML
output.  To avoid images looking too large on nowadays-normal screens,
restrict the width to 75% on such screens.

Some work is still necessary because SVG images without a viewBox
still won't scale, but that will a separate patch.

Discussion: https://www.postgresql.org/message-id/flat/6d2442d1-84a2-36ef-e014-b6d1ece8a139%40postgresql.org
2019-04-16 14:27:56 +02:00
Magnus Hagander 77bd49adba Show shared object statistics in pg_stat_database
This adds a row to the pg_stat_database view with datoid 0 and datname
NULL for those objects that are not in a database. This was added
particularly for checksums, but we were already tracking more satistics
for these objects, just not returning it.

Also add a checksum_last_failure column that holds the timestamptz of
the last checksum failure that occurred in a database (or in a
non-dataabase file), if any.

Author: Julien Rouhaud <rjuju123@gmail.com>
2019-04-12 14:04:50 +02:00
Bruce Momjian d4888a3f76 doc: adjust libpq wording to be neither/nor
Reported-by: postgresql@cohi.at

Discussion: https://postgr.es/m/155419437926.737.10876947446993402227@wrigleys.postgresql.org

Backpatch-through: 9.4
2019-04-11 13:25:34 -04:00
Peter Eisentraut 122fa9f942 doc: Fix whitespace
Author: Julien Rouhaud <rjuju123@gmail.com>
2019-04-08 22:32:46 +02:00
Peter Eisentraut c66000385f doc: Update serial explanation
The CREATE SEQUENCE command should include a data type specification,
since PostgreSQL 10.

Reported-by: mjf@pearson.co.uk
2019-04-08 22:03:48 +02:00
Peter Eisentraut 348f57ce5b doc: Add note about generated columns in foreign tables
Explain that it is not enforced that querying a generated column
returns data that is consistent with the data that was stored.  This
is similar to the note about constraints nearby.

Reported-by: Amit Langote <amitlangote09@gmail.com>
2019-04-08 13:47:46 +02:00
Fujii Masao 119dcfad98 Add vacuum_truncate reloption.
vacuum_truncate controls whether vacuum tries to truncate off
any empty pages at the end of the table. Previously vacuum always
tried to do the truncation. However, the truncation could cause
some problems; for example, ACCESS EXCLUSIVE lock needs to
be taken on the table during the truncation and can cause
the query cancellation on the standby even if hot_standby_feedback
is true. Setting this reloption to false can be helpful to avoid
such problems.

Author: Tsunakawa Takayuki
Reviewed-By: Julien Rouhaud, Masahiko Sawada, Michael Paquier, Kirk Jamison and Fujii Masao
Discussion: https://postgr.es/m/CAHGQGwE5UqFqSq1=kV3QtTUtXphTdyHA-8rAj4A=Y+e4kyp3BQ@mail.gmail.com
2019-04-08 16:43:57 +09:00
Michael Paquier e3865c3754 Tweak wording of documentation for pg_checksums
Author: Justin Pryzby
Discussion: https://postgr.es/m/20190329143210.GI5815@telsasoft.com
2019-04-08 15:30:45 +09:00
Alvaro Herrera 1c5d9270e3 psql \dP: list partitioned tables and indexes
The new command lists partitioned relations (tables and/or indexes),
possibly with their sizes, possibly including partitioned partitions;
their parents (if not top-level); if indexes show the tables they belong
to; and their descriptions.

While there are various possible improvements to this, having it in this
form is already a great improvement over not having any way to obtain
this report.

Author: Pavel Stěhule, with help from Mathias Brossard, Amit Langote and
	Justin Pryzby.
Reviewed-by: Amit Langote, Mathias Brossard, Melanie Plageman,
	Michaël Paquier, Álvaro Herrera
2019-04-07 15:07:21 -04:00
Peter Eisentraut 03f9e5cba0 Report progress of REINDEX operations
This uses the same infrastructure that the CREATE INDEX progress
reporting uses.  Add a column to pg_stat_progress_create_index to
report the OID of the index being worked on.  This was not necessary
for CREATE INDEX, but it's useful for REINDEX.

Also edit the phase descriptions a bit to be more consistent with the
source code comments.

Discussion: https://www.postgresql.org/message-id/ef6a6757-c36a-9e81-123f-13b19e36b7d7%402ndquadrant.com
2019-04-07 12:35:29 +02:00
Peter Eisentraut 106f2eb664 Cast pg_stat_progress_cluster.cluster_index_relid to oid
It's tracked internally as bigint, but when presented to the user it
should be oid.
2019-04-07 10:31:32 +02:00
Michael Paquier 249d649996 Add support TCP user timeout in libpq and the backend server
Similarly to the set of parameters for keepalive, a connection parameter
for libpq is added as well as a backend GUC, called tcp_user_timeout.

Increasing the TCP user timeout is useful to allow a connection to
survive extended periods without end-to-end connection, and decreasing
it allows application to fail faster.  By default, the parameter is 0,
which makes the connection use the system default, and follows a logic
close to the keepalive parameters in its handling.  When connecting
through a Unix-socket domain, the parameters have no effect.

Author: Ryohei Nagaura
Reviewed-by: Fabien Coelho, Robert Haas, Kyotaro Horiguchi, Kirk
Jamison, Mikalai Keida, Takayuki Tsunakawa, Andrei Yahorau
Discussion: https://postgr.es/m/EDA4195584F5064680D8130B1CA91C45367328@G01JPEXMBYT04
2019-04-06 15:23:37 +09:00