14249 Commits

Author SHA1 Message Date
Fujii Masao
462ff79669 Archive timeline history files in standby if archive_mode is set to "always".
Previously the standby server didn't archive timeline history files
streamed from the primary even when archive_mode is set to "always",
while it archives the streamed WAL files. This could cause the PITR to
fail because there was no required timeline history file in the archive.
The cause of this issue was that walreceiver didn't mark those files as
ready for archiving.

This commit makes walreceiver mark those streamed timeline history
files as ready for archiving if archive_mode=always. Then the archiver
process archives the marked timeline history files.

Back-patch to all supported versions.

Reported-by: Grigory Smolkin
Author: Grigory Smolkin, Fujii Masao
Reviewed-by: David Zhang, Anastasia Lubennikova
Discussion: https://postgr.es/m/54b059d4-2b48-13a4-6f43-95a087c92367@postgrespro.ru
2020-09-29 16:24:47 +09:00
Peter Eisentraut
a089aa122b doc: Don't hide the "Up" link when it is the same as "Home"
The original stylesheets seemed to think this was a good idea, but our
users find it confusing and unhelpful, so undo that logic.

Reported-by: Fabien COELHO <coelho@cri.ensmp.fr>
Discussion: https://www.postgresql.org/message-id/flat/alpine.DEB.2.22.394.2006210914370.859381%40pseudo
2020-09-12 20:31:48 +02:00
Peter Eisentraut
d0b585e861 doc: Remove buggy ICU collation from documentation
We have had multiple reports that point to the
'@colReorder=latn-digit' collation customization being buggy.  We have
reported this to ICU and are waiting for a fix.  In the meantime,
remove references to this from the documentation and replace it by
another reordering example.  Apparently, many users have been picking
up this example specifically from the documentation.

Author: Jehan-Guillaume de Rorthais <jgdr@dalibo.com>
Discussion: https://www.postgresql.org/message-id/flat/153201618542.1404.3611626898935613264%40wrigleys.postgresql.org
2020-09-10 15:36:32 +02:00
Magnus Hagander
e30f1aa358 Fix title in reference section
Reported-by: Robert Kahlert
Author: Daniel Gustafsson
2020-09-10 14:16:38 +02:00
Michael Paquier
447c1cb2f6 doc: Fix some grammar and inconsistencies
Some comments are fixed while on it.

Author: Justin Pryzby
Discussion: https://postgr.es/m/20200818171702.GK17022@telsasoft.com
Backpatch-through: 9.6
2020-09-10 15:50:50 +09:00
Bruce Momjian
1fa1f2c39e doc: clarify that max_wal_size is "during" checkpoints
Previous wording was "between".

Reported-by: Pavel Luzanov

Discussion: https://postgr.es/m/26906a54-d7cb-2f8e-eed7-e31660024694@postgrespro.ru

Backpatch-through: 9.5
2020-09-01 17:00:10 -04:00
Alvaro Herrera
f00f5e0c11
Raise error on concurrent drop of partitioned index
We were already raising an error for DROP INDEX CONCURRENTLY on a
partitioned table, albeit a different and confusing one:
  ERROR:  DROP INDEX CONCURRENTLY must be first action in transaction

Change that to throw a more comprehensible error:
  ERROR:  cannot drop partitioned index \"%s\" concurrently

Michael Paquier authored the test case for indexes on temporary
partitioned tables.

Backpatch to 11, where indexes on partitioned tables were added.

Reported-by: Jan Mussler <jan.mussler@zalando.de>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/16594-d2956ca909585067@postgresql.org
2020-09-01 13:40:43 -04:00
Bruce Momjian
b235936a1d doc: add commas after 'i.e.' and 'e.g.'
This follows the American format,
https://jakubmarian.com/comma-after-i-e-and-e-g/. There is no intention
of requiring this format for future text, but making existing text
consistent every few years makes sense.

Discussion: https://postgr.es/m/20200825183619.GA22369@momjian.us

Backpatch-through: 9.5
2020-08-31 18:33:37 -04:00
Bruce Momjian
c3cb3716ad pg_upgrade doc: mention saving postgresql.conf.auto files
Also mention files included by postgresql.conf.

Reported-by: Álvaro Herrera

Discussion: https://postgr.es/m/08AD4526-75AB-457B-B2DD-099663F28040@yesql.se

Backpatch-through: 9.5
2020-08-31 17:36:22 -04:00
Bruce Momjian
eb7f602478 docs: in mapping SQL to C data types, timestamp isn't a pointer
It is an int64.

Reported-by: ajulien@shaktiware.fr

Discussion: https://postgr.es/m/159845038271.24995.15682121015698255155@wrigleys.postgresql.org

Backpatch-through: 9.5
2020-08-31 17:05:53 -04:00
Bruce Momjian
5e22362d31 doc: cross-link file-fdw and CSV config log sections
There is an file-fdw example that reads the server config file, so cross
link them.

Reported-by: Oleg Samoilov

Discussion: https://postgr.es/m/159800192078.2886.10431506404995508950@wrigleys.postgresql.org

Backpatch-through: 9.5
2020-08-31 16:59:58 -04:00
Bruce Momjian
bdfd83f4a4 docs: clarify intermediate certificate creation instructions
Specifically, explain the v3_ca openssl specification.

Discussion: https://postgr.es/m/20200824175653.GA32411@momjian.us

Backpatch-through: 9.5
2020-08-31 16:21:03 -04:00
Bruce Momjian
11d0ed6a05 docs: replace "stable storage" with "durable" in descriptions
For PG, "durable storage" has a clear meaning, while "stable storage"
does not, so use the former.

Discussion: https://postgr.es/m/20200817165222.GA31806@momjian.us

Backpatch-through: 9.5
2020-08-31 15:23:18 -04:00
Bruce Momjian
e8e15385a1 doc: improve description of subscripting of arrays
It wasn't clear the non-integers are cast to integers for subscripting,
rather than throwing an error.

Reported-by: sean@materialize.io

Discussion: https://postgr.es/m/159538675800.624.7728794628229799531@wrigleys.postgresql.org

Backpatch-through: 9.5
2020-08-31 13:49:17 -04:00
Bruce Momjian
104a7dad36 docs: improve 'capitals' inheritance example
Adds constraints and improves wording.

Reported-by: 2552891@gmail.com

Discussion: https://postgr.es/m/159586122762.680.1361378513036616007@wrigleys.postgresql.org

Backpatch-through: 9.5
2020-08-31 13:43:04 -04:00
Bruce Momjian
bed05fff6f doc: clarify the useful features of procedures
This was not clearly documented when procedures were added in PG 11.

Reported-by: Robin Abbi

Discussion: https://postgr.es/m/CAGmg_NX327KKVuJmbWZD=pGutYFxzZjX1rU+3ji8UuX=8ONn9Q@mail.gmail.com

Backpatch-through: 11
2020-08-31 13:20:04 -04:00
Magnus Hagander
d58dea6ae0 Fix docs bug stating file_fdw requires absolute paths
It has always (since the first commit) worked with relative paths, so
use the same wording as other parts of the documentation.

Author: Bruce Momjian
Discussion: https://postgr.es/m/CABUevExx-hm=cit+A9LeKBH39srvk8Y2tEZeEAj5mP8YfzNKUg@mail.gmail.com
2020-08-31 13:06:08 +02:00
Tom Lane
d1ee6ce4c9 Mark factorial operator, and postfix operators in general, as deprecated.
Back-patch key parts of 4c5cf5431 and 6ca547cf7 into stable branches.
I didn't touch pg_description entries here, so it's purely a docs
change; and I didn't fool with any examples either.  The main point
is so that anyone who's wondering if factorial() exists in the stable
branches will be reassured.

Mark Dilger and John Naylor, with some adjustments by me

Discussion: https://postgr.es/m/BE2DF53D-251A-4E26-972F-930E523580E9@enterprisedb.com
2020-08-30 16:03:19 -04:00
Bruce Momjian
b8d768813a docs: client certificates are always sent to the server
They are not "requested" by the server.

Reported-by: Kyotaro Horiguchi

Discussion: https://postgr.es/m/20200825.155320.986648039251743210.horikyota.ntt@gmail.com

Backpatch-through: 9.5
2020-08-25 09:53:12 -04:00
Bruce Momjian
ac0ad75bf7 docs: improve description of how to handle multiple databases
This is a redesign of the intro to the managing databases chapter.

Discussion: https://postgr.es/m/159586122762.680.1361378513036616007@wrigleys.postgresql.org

Author: David G. Johnston

Backpatch-through: 9.5
2020-08-21 20:23:09 -04:00
Bruce Momjian
1e6edbfa23 docs: add COMMENT examples for new features, rename rtree
Reported-by: Jürgen Purtz

Discussion: https://postgr.es/m/15ec5428-d46a-1725-f38d-44986a977abb@purtz.de

Author: Jürgen Purtz

Backpatch-through: 11
2020-08-21 18:29:37 -04:00
Tom Lane
fd55df04ed Doc: fix description of UNION/CASE/etc type unification.
The description of what select_common_type() does was not terribly
accurate.  Improve it.

David Johnston and Tom Lane

Discussion: https://postgr.es/m/1019930.1597613200@sss.pgh.pa.us
2020-08-17 15:40:07 -04:00
Michael Paquier
7aa0cae752 doc: Fix description about bgwriter and checkpoint in HA section
Since 806a2ae, the work of the bgwriter is split the checkpointer, but a
portion of the documentation did not get the message.

Author: Masahiko Sawada
Discussion: https://postgr.es/m/CA+fd4k6jXxjAtjMVC=wG3=QGpauZBtcgN3Jhw+oV7zXGKVLKzQ@mail.gmail.com
Backpatch-through: 9.5
2020-08-17 10:24:34 +09:00
Noah Misch
d4031d7846 Prevent concurrent SimpleLruTruncate() for any given SLRU.
The SimpleLruTruncate() header comment states the new coding rule.  To
achieve this, add locktype "frozenid" and two LWLocks.  This closes a
rare opportunity for data loss, which manifested as "apparent
wraparound" or "could not access status of transaction" errors.  Data
loss is more likely in pg_multixact, due to released branches' thin
margin between multiStopLimit and multiWrapLimit.  If a user's physical
replication primary logged ":  apparent wraparound" messages, the user
should rebuild standbys of that primary regardless of symptoms.  At less
risk is a cluster having emitted "not accepting commands" errors or
"must be vacuumed" warnings at some point.  One can test a cluster for
this data loss by running VACUUM FREEZE in every database.  Back-patch
to 9.5 (all supported versions).

Discussion: https://postgr.es/m/20190218073103.GA1434723@rfd.leadboat.com
2020-08-15 10:15:57 -07:00
Tom Lane
250aaa2de9 Fix postmaster's behavior during smart shutdown.
Up to now, upon receipt of a SIGTERM ("smart shutdown" command), the
postmaster has immediately killed all "optional" background processes,
and subsequently refused to launch new ones while it's waiting for
foreground client processes to exit.  No doubt this seemed like an OK
policy at some point; but it's a pretty bad one now, because it makes
for a seriously degraded environment for the remaining clients:

* Parallel queries are killed, and new ones fail to launch. (And our
parallel-query infrastructure utterly fails to deal with the case
in a reasonable way --- it just hangs waiting for workers that are
not going to arrive.  There is more work needed in that area IMO.)

* Autovacuum ceases to function.  We can tolerate that for awhile,
but if bulk-update queries continue to run in the surviving client
sessions, there's eventually going to be a mess.  In the worst case
the system could reach a forced shutdown to prevent XID wraparound.

* The bgwriter and walwriter are also stopped immediately, likely
resulting in performance degradation.

Hence, let's rearrange things so that the only immediate change in
behavior is refusing to let in new normal connections.  Once the last
normal connection is gone, shut everything down as though we'd received
a "fast" shutdown.  To implement this, remove the PM_WAIT_BACKUP and
PM_WAIT_READONLY states, instead staying in PM_RUN or PM_HOT_STANDBY
while normal connections remain.  A subsidiary state variable tracks
whether or not we're letting in new connections in those states.

This also allows having just one copy of the logic for killing child
processes in smart and fast shutdown modes.  I moved that logic into
PostmasterStateMachine() by inventing a new state PM_STOP_BACKENDS.

Back-patch to 9.6 where parallel query was added.  In principle
this'd be a good idea in 9.5 as well, but the risk/reward ratio
is not as good there, since lack of autovacuum is not a problem
during typical uses of smart shutdown.

Per report from Bharath Rupireddy.

Patch by me, reviewed by Thomas Munro

Discussion: https://postgr.es/m/CALj2ACXAZ5vKxT9P7P89D87i3MDO9bfS+_bjMHgnWJs8uwUOOw@mail.gmail.com
2020-08-14 13:26:57 -04:00
Tom Lane
25180875cb Stamp 11.9. 2020-08-10 17:17:40 -04:00
Tom Lane
6f57b9bf39 Last-minute updates for release notes.
Security: CVE-2020-14349, CVE-2020-14350
2020-08-10 15:35:46 -04:00
Noah Misch
613ed8a588 Document clashes between logical replication and untrusted users.
Back-patch to v10, which introduced logical replication.

Security: CVE-2020-14349
2020-08-10 09:22:59 -07:00
Tom Lane
afa358786b Make contrib modules' installation scripts more secure.
Hostile objects located within the installation-time search_path could
capture references in an extension's installation or upgrade script.
If the extension is being installed with superuser privileges, this
opens the door to privilege escalation.  While such hazards have existed
all along, their urgency increases with the v13 "trusted extensions"
feature, because that lets a non-superuser control the installation path
for a superuser-privileged script.  Therefore, make a number of changes
to make such situations more secure:

* Tweak the construction of the installation-time search_path to ensure
that references to objects in pg_catalog can't be subverted; and
explicitly add pg_temp to the end of the path to prevent attacks using
temporary objects.

* Disable check_function_bodies within installation/upgrade scripts,
so that any security gaps in SQL-language or PL-language function bodies
cannot create a risk of unwanted installation-time code execution.

* Adjust lookup of type input/receive functions and join estimator
functions to complain if there are multiple candidate functions.  This
prevents capture of references to functions whose signature is not the
first one checked; and it's arguably more user-friendly anyway.

* Modify various contrib upgrade scripts to ensure that catalog
modification queries are executed with secure search paths.  (These
are in-place modifications with no extension version changes, since
it is the update process itself that is at issue, not the end result.)

Extensions that depend on other extensions cannot be made fully secure
by these methods alone; therefore, revert the "trusted" marking that
commit eb67623c9 applied to earthdistance and hstore_plperl, pending
some better solution to that set of issues.

Also add documentation around these issues, to help extension authors
write secure installation scripts.

Patch by me, following an observation by Andres Freund; thanks
to Noah Misch for review.

Security: CVE-2020-14350
2020-08-10 10:44:43 -04:00
Tom Lane
ae2d34478c Release notes for 12.4, 11.9, 10.14, 9.6.19, 9.5.23. 2020-08-08 20:01:41 -04:00
Bruce Momjian
b144edbf7d doc: clarify "state" table reference in tutorial
Reported-by: Vyacheslav Shablistyy

Discussion: https://postgr.es/m/159586122762.680.1361378513036616007@wrigleys.postgresql.org

Backpatch-through: 9.5
2020-08-05 17:12:10 -04:00
Tom Lane
995c53b449 Doc: fix obsolete info about allowed range of TZ offsets in timetz.
We've allowed UTC offsets up to +/- 15:59 since commit cd0ff9c0f, but
that commit forgot to fix the documentation about timetz.

Per bug #16571 from osdba.

Discussion: https://postgr.es/m/16571-eb7501598de78c8a@postgresql.org
2020-08-03 13:11:16 -04:00
Tatsuo Ishii
065699590a Doc: fix high availability solutions comparison.
In "High Availability, Load Balancing, and Replication" chapter,
certain descriptions of Pgpool-II were not correct at this point.  It
does not need conflict resolution. Also "Multiple-Server Parallel
Query Execution" is not supported anymore.

Discussion: https://postgr.es/m/20200726.230128.53842489850344110.t-ishii%40sraoss.co.jp
Author: Tatsuo Ishii
Reviewed-by: Bruce Momjian
Backpatch-through: 9.5
2020-07-31 07:49:00 +09:00
Michael Paquier
255c707c87 doc: Mention index references in pg_inherits
Partitioned indexes are also registered in pg_inherits, but the
description of this catalog did not reflect that.

Author: Dagfinn Ilmari Mannsåker
Discussion: https://postgr.es/m/87k0ynj35y.fsf@wibble.ilmari.org
Backpatch-through: 11
2020-07-30 15:49:01 +09:00
David Rowley
baecd2715b Doc: Improve documentation for pg_jit_available()
Per complaint from Scott Ribe. Based on wording suggestion from Tom Lane.

Discussion: https://postgr.es/m/1956E806-1468-4417-9A9D-235AE1D5FE1A@elevated-dev.com
Backpatch-through: 11, where pg_jit_available() was added
2020-07-28 22:52:58 +12:00
Peter Eisentraut
807dbce4b6 doc: Document that ssl_ciphers does not affect TLS 1.3
TLS 1.3 uses a different way of specifying ciphers and a different
OpenSSL API.  PostgreSQL currently does not support setting those
ciphers.  For now, just document this.  In the future, support for
this might be added somehow.

Reviewed-by: Jonathan S. Katz <jkatz@postgresql.org>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
2020-07-23 20:38:45 +02:00
Tom Lane
f451029db8 Assert that we don't insert nulls into attnotnull catalog columns.
The executor checks for this error, and so does the bootstrap catalog
loader, but we never checked for it in retail catalog manipulations.
The folly of that has now been exposed, so let's add assertions
checking it.  Checking in CatalogTupleInsert[WithInfo] and
CatalogTupleUpdate[WithInfo] should be enough to cover this.

Back-patch to v10; the aforesaid functions didn't exist before that,
and it didn't seem worth adapting the patch to the oldest branches.
But given the risk of JIT crashes, I think we certainly need this
as far back as v11.

Pre-v13, we have to explicitly exclude pg_subscription.subslotname
and pg_subscription_rel.srsublsn from the checks, since they are
mismarked.  (Even if we change our mind about applying BKI_FORCE_NULL
in the branch tips, it doesn't seem wise to have assertions that
would fire in existing databases.)

Discussion: https://postgr.es/m/298837.1595196283@sss.pgh.pa.us
2020-07-21 12:38:08 -04:00
Tom Lane
99b0c5da3e Avoid direct C access to possibly-null pg_subscription_rel.srsublsn.
This coding technique is unsafe, since we'd be accessing off the end
of the tuple if the field is null.  SIGSEGV is pretty improbable, but
perhaps not impossible.  Also, returning garbage for the LSN doesn't
seem like a great idea, even if callers aren't looking at it today.

Also update docs to point out explicitly that
pg_subscription.subslotname and pg_subscription_rel.srsublsn
can be null.

Perhaps we should mark these two fields BKI_FORCE_NULL, so that
they'd be correctly labeled in databases that are initdb'd in the
future.  But we can't force that for existing databases, and on
balance it's not too clear that having a mix of different catalog
contents in the field would be wise.

Apply to v10 (where this code came in) through v12.  Already
fixed in v13 and HEAD.

Discussion: https://postgr.es/m/732838.1595278439@sss.pgh.pa.us
2020-07-21 11:40:47 -04:00
Michael Paquier
dcd6718017 doc: Refresh more URLs in the docs
This updates some URLs that are redirections, mostly to an equivalent
using https.  One URL referring to generalized partial indexes was
outdated.

Author: Kyotaro Horiguchi
Discussion: https://postgr.es/m/20200717.121308.1369606287593685396.horikyota.ntt@gmail.com
Backpatch-through: 9.5
2020-07-18 22:43:49 +09:00
Tom Lane
0ecd36ee0e Doc: update or remove dead external links.
Re-point comp.ai.genetic FAQ link to a more stable address.

Remove stale links to AIX documentation; we don't really need to
tell AIX users how to use their systems.

Remove stale links to HP documentation about SSL.  We've had to
update those twice before, making it increasingly obvious that
HP does not intend them to be stable landing points.  They're
not particularly authoritative, either.  (This change effectively
reverts bbd3bdba3.)

Daniel Gustafsson and Álvaro Herrera, per a gripe from
Kyotaro Horiguchi.  Back-patch, since these links are
just as dead in the back branches.

Discussion: https://postgr.es/m/20200709.161226.204639179120026914.horikyota.ntt@gmail.com
2020-07-10 13:16:00 -04:00
Fujii Masao
08952572a7 doc: Correct the description about the length of pg_stat_activity.query.
pg_stat_activity.query text is truncated at 1024 bytes. But previously
the document described that it's truncated at 1024 characters.
This was not accurate when considering multibyte characters.

Back-patch to v10 where this inaccurate description was added.

Author: Atsushi Torikoshi
Reviewed-by: Daniel Gustafsson, Fujii Masao
Discussion: https://postgr.es/m/cd5b49a5a14e887542f5f569c1c6bde2@oss.nttdata.com
2020-07-09 13:36:24 +09:00
Michael Paquier
d51155544b doc: Fix incorrect reference to textout in plpgsql examples
This error has survived for 22 years, and has been introduced by
da63386.

Reported-by: Erwin Brandstetter
Discussion: https://postgr.es/m/CAGHENJ57wogGOvGXo5LgWYcqswxafLck8ELqHDR+zrkTPgs_OQ@mail.gmail.com
Backpatch-through: 9.5
2020-07-05 19:36:22 +09:00
Tom Lane
ef799bdd04 Clamp total-tuples estimates for foreign tables to ensure planner sanity.
After running GetForeignRelSize for a foreign table, adjust rel->tuples
to be at least as large as rel->rows.  This prevents bizarre behavior
in estimate_num_groups() and perhaps other places, especially in the
scenario where rel->tuples is zero because pg_class.reltuples is
(suggesting that ANALYZE has never been run for the table).  As things
stood, we'd end up estimating one group out of any GROUP BY on such a
table, whereas the default group-count estimate is more likely to result
in a sane plan.

Also, clarify in the documentation that GetForeignRelSize has the option
to override the rel->tuples value if it has a better idea of what to use
than what is in pg_class.reltuples.

Per report from Jeff Janes.  Back-patch to all supported branches.

Patch by me; thanks to Etsuro Fujita for review

Discussion: https://postgr.es/m/CAMkU=1xNo9cnan+Npxgz0eK7394xmjmKg-QEm8wYG9P5-CcaqQ@mail.gmail.com
2020-07-03 19:01:21 -04:00
Bruce Momjian
81b244e78b doc: clarify that storage parameter values are optional
In a few cases, the documented syntax specified storage parameter values
as required.

Reported-by: galiev_mr@taximaxim.ru

Discussion: https://postgr.es/m/159283163235.684.4482737698910467437@wrigleys.postgresql.org

Backpatch-through: 9.5
2020-06-30 12:26:51 -04:00
Bruce Momjian
457942e188 doc: change pg_upgrade wal_level to be not minimal
Previously it was specified to be only replica.

Discussion: https://postgr.es/m/20200618180058.GK7349@momjian.us

Backpatch-through: 9.5
2020-06-30 11:55:53 -04:00
Noah Misch
b2bf22c1e5 Fix documentation of "must be vacuumed within" warning.
Warnings start 10M transactions before xidStopLimit, which is 11M
transactions before wraparound.  The sample WARNING output showed a
value greater than 11M, and its HINT message predated commit
25ec228ef760eb91c094cc3b6dea7257cc22ffb5.  Hence, the sample was
impossible.  Back-patch to 9.5 (all supported versions).
2020-06-27 22:05:07 -07:00
Bruce Momjian
4a12bfe21a doc: mention trigger helper functions in CREATE TRIGGER docs
Reported-by: petermpallesen@gmail.com

Discussion: https://postgr.es/m/159195294959.673.5752624528747900508@wrigleys.postgresql.org

Backpatch-through: 9.5
2020-06-25 18:33:28 -04:00
Bruce Momjian
bf4f195925 docs: clarify that CREATE DATABASE does not copy db permissions
That is, those database permissions set by GRANT.

Diagnosed-by: Joseph Nahmias

Discussion: https://postgr.es/m/20200614072613.GA21852@nahmias.net

Backpatch-through: 9.5
2020-06-25 18:22:44 -04:00
Tom Lane
e7c183cd1f Future-proof regression tests against possibly-missing posixrules file.
The IANA time zone folk have deprecated use of a "posixrules" file in
the tz database.  While for now it's our choice whether to keep
supplying one in our own builds, installations built with
--with-system-tzdata will soon be needing to cope with that file not
being present, at least on some platforms.

This causes a problem for the horology test, which expected the
nonstandard POSIX zone spec "CST7CDT" to apply pre-2007 US daylight
savings rules.  That does happen if the posixrules file supplies such
information, but otherwise the test produces undesired results.
To fix, add an explicit transition date rule that matches 2005 practice.
(We could alternatively have switched the test to use some real time
zone, but it seems useful to have coverage of this type of zone spec.)

While at it, update a documentation example that also relied on
"CST7CDT"; use a real-world zone name instead.  Also, document why
the zone names EST5EDT, CST6CDT, MST7MDT, PST8PDT aren't subject to
similar failures when "posixrules" is missing.

Back-patch to all supported branches, since the hazard is the same
for all.

Discussion: https://postgr.es/m/1665379.1592581287@sss.pgh.pa.us
2020-06-19 13:55:21 -04:00
Tom Lane
070f490053 Doc: document POSIX-style time zone specifications in full.
We'd glossed over most of this complexity for years, but it's hard
to avoid writing it all down now, so that we can explain what happens
when there's no "posixrules" file in the IANA time zone database.
That was at best a tiny minority situation till now, but it's likely
to become quite common in the future, so we'd better explain it.

Nonetheless, we don't really encourage people to use POSIX zone specs;
picking a named zone is almost always what you really want, unless
perhaps you're stuck with an out-of-date zone database.  Therefore,
let's shove all this detail into an appendix.

Patch by me; thanks to Robert Haas for help with some awkward wording.

Discussion: https://postgr.es/m/1390.1562258309@sss.pgh.pa.us
2020-06-18 16:27:42 -04:00