The builtin C.UTF-8 locale has similar semantics to the libc locale of
the same name. That is, code point sort order (fast, memcmp-based)
combined with Unicode semantics for character operations such as
pattern matching, regular expressions, and
LOWER()/INITCAP()/UPPER(). The character semantics are based on
Unicode simple case mappings.
The builtin provider's C.UTF-8 offers several important advantages
over libc:
* faster sorting -- benefits from additional optimizations such as
abbreviated keys and varstrfastcmp_c
* faster case conversion, e.g. LOWER(), at least compared with some
libc implementations
* available on all platforms with identical semantics, and the
semantics are stable, testable, and documentable within a given
Postgres major version
Being based on memcmp, the builtin C.UTF-8 locale does not offer
natural language sort order. But it is an improvement for most use
cases that might otherwise use libc's "C.UTF-8" locale, as well as
many use cases that use libc's "C" locale.
Discussion: https://postgr.es/m/ff4c2f2f9c8fc7ca27c1c24ae37ecaeaeaff6b53.camel%40j-davis.com
Reviewed-by: Daniel Vérité, Peter Eisentraut, Jeremy Schneider
Historically we've printed SubPlan expression nodes as "(SubPlan N)",
which is pretty uninformative. Trying to reproduce the original SQL
for the subquery is still as impractical as before, and would be
mighty verbose as well. However, we can still do better than that.
Displaying the "testexpr" when present, and adding a keyword to
indicate the SubLinkType, goes a long way toward showing what's
really going on.
In addition, this patch gets rid of EXPLAIN's use of "$n" to represent
subplan and initplan output Params. Instead we now print "(SubPlan
N).colX" or "(InitPlan N).colX" to represent the X'th output column
of that subplan. This eliminates confusion with the use of "$n" to
represent PARAM_EXTERN Params, and it's useful for the first part of
this change because it eliminates needing some other indication of
which subplan is referenced by a SubPlan that has a testexpr.
In passing, this adds simple regression test coverage of the
ROWCOMPARE_SUBLINK code paths, which were entirely unburdened
by testing before.
Tom Lane and Dean Rasheed, reviewed by Aleksander Alekseev.
Thanks to Chantal Keller for raising the question of whether
this area couldn't be improved.
Discussion: https://postgr.es/m/2838538.1705692747@sss.pgh.pa.us
Based on comments from Peter Eisentraut.
* Document CREATE DATABASE ... BUILTIN_LOCALE.
* Determine required encoding based on locale name for CREATE
COLLATION. Use -1 for "C" (requires catversion bump).
* initdb output fixups.
* Make ctype_is_c a constant true for now.
* Fixups to ICU 010_create_database.pl test.
Discussion: https://postgr.es/m/4135cf11-206d-40ed-96c0-9363c1232379@eisentraut.org
This allows a RETURNING clause to be appended to a MERGE query, to
return values based on each row inserted, updated, or deleted. As with
plain INSERT, UPDATE, and DELETE commands, the returned values are
based on the new contents of the target table for INSERT and UPDATE
actions, and on its old contents for DELETE actions. Values from the
source relation may also be returned.
As with INSERT/UPDATE/DELETE, the output of MERGE ... RETURNING may be
used as the source relation for other operations such as WITH queries
and COPY commands.
Additionally, a special function merge_action() is provided, which
returns 'INSERT', 'UPDATE', or 'DELETE', depending on the action
executed for each row. The merge_action() function can be used
anywhere in the RETURNING list, including in arbitrary expressions and
subqueries, but it is an error to use it anywhere outside of a MERGE
query's RETURNING list.
Dean Rasheed, reviewed by Isaac Morland, Vik Fearing, Alvaro Herrera,
Gurjeet Singh, Jian He, Jeff Davis, Merlin Moncure, Peter Eisentraut,
and Wolfgang Walther.
Discussion: http://postgr.es/m/CAEZATCWePEGQR5LBn-vD6SfeLZafzEm2Qy_L_Oky2=qw2w3Pzg@mail.gmail.com
This function returns the chunk_id of an on-disk TOASTed value. If
the value is un-TOASTed or not on-disk, it returns NULL. This is
useful for identifying which values are actually TOASTed and for
investigating "unexpected chunk number" errors.
Bumps catversion.
Author: Yugo Nagata
Reviewed-by: Jian He
Discussion: https://postgr.es/m/20230329105507.d764497456eeac1ca491b5bd%40sraoss.co.jp
New provider for collations, like "libc" or "icu", but without any
external dependency.
Initially, the only locale supported by the builtin provider is "C",
which is identical to the libc provider's "C" locale. The libc
provider's "C" locale has always been treated as a special case that
uses an internal implementation, without using libc at all -- so the
new builtin provider uses the same implementation.
The builtin provider's locale is independent of the server environment
variables LC_COLLATE and LC_CTYPE. Using the builtin provider, the
database collation locale can be "C" while LC_COLLATE and LC_CTYPE are
set to "en_US", which is impossible with the libc provider.
By offering a new builtin provider, it clarifies that the semantics of
a collation using this provider will never depend on libc, and makes
it easier to document the behavior.
Discussion: https://postgr.es/m/ab925f69-5f9d-f85e-b87c-bd2a44798659@joeconway.com
Discussion: https://postgr.es/m/dd9261f4-7a98-4565-93ec-336c1c110d90@manitou-mail.org
Discussion: https://postgr.es/m/ff4c2f2f9c8fc7ca27c1c24ae37ecaeaeaff6b53.camel%40j-davis.com
Reviewed-by: Daniel Vérité, Peter Eisentraut, Jeremy Schneider
pg_stat_checkpointer contains statistics for checkpoints and restartpoints.
Before 12915a58ee documentation said only about checkpoints implying that
restartpoint is the variation of checkpoint. 12915a58ee introduced
new separate statistics fields for restartpoints. This commit explicitly
documents fields that are relevant for both checkpoints and restartpoints.
Reported-by: Magnus Hagander
Discussion: https://postgr.es/m/CABUevExav5-SR0x%2BG9kBUMV0G8XsvSUfuyyqmYBBJi6VHns6sw%40mail.gmail.com
Reviewed-by: Anton A. Melnikov
Roles with MAINTAIN on a relation may run VACUUM, ANALYZE, REINDEX,
REFRESH MATERIALIZE VIEW, CLUSTER, and LOCK TABLE on the relation.
Roles with privileges of pg_maintain may run those same commands on
all relations.
This was previously committed for v16, but it was reverted in
commit 151c22deee due to concerns about search_path tricks that
could be used to escalate privileges to the table owner. Commits
2af07e2f74, 59825d1639, and c7ea3f4229 resolved these concerns by
restricting search_path when running maintenance commands.
Bumps catversion.
Reviewed-by: Jeff Davis
Discussion: https://postgr.es/m/20240305161235.GA3478007%40nathanxps13
Before this patch, if you took a full backup on server A and then
tried to use the backup manifest to take an incremental backup on
server B, it wouldn't know that the manifest was from a different
server and so the incremental backup operation could potentially
complete without error. When you later tried to run pg_combinebackup,
you'd find out that your incremental backup was and always had been
invalid. That's poor timing, because nobody likes finding out about
backup problems only at restore time.
With this patch, you'll get an error when trying to take the (invalid)
incremental backup, which seems a lot nicer.
Amul Sul, revised by me. Review by Michael Paquier.
Discussion: http://postgr.es/m/CA+TgmoYLZzbSAMM3cAjV4Y+iCRZn-bR9H2+Mdz7NdaJFU1Zb5w@mail.gmail.com
In the synopsis, make the syntax for merge_update consistent with the
syntax for a plain UPDATE command. It was missing the optional "ROW"
keyword that can be used in a multi-column assignment, and the option
to assign from a multi-column subquery, both of which have been
supported by MERGE since it was introduced.
In the parameters section for the with_query parameter, mention that
WITH RECURSIVE isn't supported, since this is different from plain
INSERT, UPDATE, and DELETE commands. While at it, move that entry to
the top of the list, for consistency with the other pages.
Back-patch to v15, where MERGE was introduced.
Discussion: https://postgr.es/m/CAEZATCWoQyWkMFfu7JXXQr8dA6%3DgxjhYzgpuBP2oz0QoJTxGWw%40mail.gmail.com
The existing PQcancel API uses blocking IO, which makes PQcancel
impossible to use in an event loop based codebase without blocking the
event loop until the call returns. It also doesn't encrypt the
connection over which the cancel request is sent, even when the original
connection required encryption.
This commit adds a PQcancelConn struct and assorted functions, which
provide a better mechanism of sending cancel requests; in particular all
the encryption used in the original connection are also used in the
cancel connection. The main entry points are:
- PQcancelCreate creates the PQcancelConn based on the original
connection (but does not establish an actual connection).
- PQcancelStart can be used to initiate non-blocking cancel requests,
using encryption if the original connection did so, which must be
pumped using
- PQcancelPoll.
- PQcancelReset puts a PQcancelConn back in state so that it can be
reused to send a new cancel request to the same connection.
- PQcancelBlocking is a simpler-to-use blocking API that still uses
encryption.
Additional functions are
- PQcancelStatus, mimicks PQstatus;
- PQcancelSocket, mimicks PQcancelSocket;
- PQcancelErrorMessage, mimicks PQerrorMessage;
- PQcancelFinish, mimicks PQfinish.
Author: Jelte Fennema-Nio <postgres@jeltef.nl>
Reviewed-by: Denis Laxalde <denis.laxalde@dalibo.com>
Discussion: https://postgr.es/m/AM5PR83MB0178D3B31CA1B6EC4A8ECC42F7529@AM5PR83MB0178.EURPRD83.prod.outlook.com
Presently, reindexdb's --table, --schema, --index, and --system
options cannot be used together with --all, i.e., you cannot
specify objects to process in all databases. This commit removes
this unnecessary restriction. Furthermore, it removes the
restriction that --system cannot be used with --table, --schema,
and --index. There is no such restriction for the latter options,
and there is no technical reason to disallow these combinations.
Reviewed-by: Kyotaro Horiguchi, Dean Rasheed
Discussion: https://postgr.es/m/20230628232402.GA1954626%40nathanxps13
Presently, clusterdb's --table option cannot be used together with
--all, i.e., you cannot specify tables to process in all databases.
This commit removes this unnecessary restriction. In passing,
change the synopsis in the documentation to use "[option...]"
instead of "[--verbose | -v]". There are other general-purpose
options (e.g., --quiet and --echo), but the synopsis currently only
lists --verbose.
Reviewed-by: Kyotaro Horiguchi, Dean Rasheed
Discussion: https://postgr.es/m/20230628232402.GA1954626%40nathanxps13
The list of connection statuses that PQstatus might return during an
asynchronous connection attempt was outdated:
1. CONNECTION_SETENV is never returned anymore and is only part of the
enum for backwards compatibility, so remove it from the docs.
2. CONNECTION_CHECK_STANDBY and CONNECTION_GSS_STARTUP were not listed,
so add them.
CONNECTION_NEEDED and CONNECTION_CHECK_TARGET are not listed in the docs
on purpose, since these are internal states that can never be observed
by a caller of PQstatus.
Author: Jelte Fennema-Nio <postgres@jeltef.nl>
Discussion: https://postgr.es/m/CAGECzQRb21spiiykQ48rzz8w+Hcykz+mB2_hxR65D9Qk6nnw=w@mail.gmail.com
Presently, vacuumdb's --table, --schema, and --exclude-schema
options cannot be used together with --all, i.e., you cannot
specify tables or schemas to process in all databases. This commit
removes this unnecessary restriction, thus enabling potentially
useful commands like "vacuumdb --all --schema pg_catalog".
Reviewed-by: Kyotaro Horiguchi, Dean Rasheed
Discussion: https://postgr.es/m/20230628232402.GA1954626%40nathanxps13
We expect the 'two_phase' and 'failover' properties to match between the
slot on the publisher and a subscription option on the subscriber.
Otherwise, the slot on the publisher may behave differently from what the
subscription's failover option says.
Author: Bertrand Drouvot
Reviewed-by: Peter Smith, Tristen Raab, Amit Kapila
Discussion: https://postgr.es/m/ZbkYrLPhH+RxpZlW@ip-10-97-1-34.eu-west-3.compute.internal
Rename pg_collation.colliculocale to colllocale, and
pg_database.daticulocale to datlocale. These names reflects that the
fields will be useful for the upcoming builtin provider as well, not
just for ICU.
This is purely a rename; no changes to the meaning of the fields.
Discussion: https://postgr.es/m/ff4c2f2f9c8fc7ca27c1c24ae37ecaeaeaff6b53.camel%40j-davis.com
Reviewed-by: Peter Eisentraut
This patch provides a way to ensure that physical standbys that are
potential failover candidates have received and flushed changes before
the primary server making them visible to subscribers. Doing so guarantees
that the promoted standby server is not lagging behind the subscribers
when a failover is necessary.
The logical walsender now guarantees that all local changes are sent and
flushed to the standby servers corresponding to the replication slots
specified in 'standby_slot_names' before sending those changes to the
subscriber.
Additionally, the SQL functions pg_logical_slot_get_changes,
pg_logical_slot_peek_changes and pg_replication_slot_advance are modified
to ensure that they process changes for failover slots only after physical
slots specified in 'standby_slot_names' have confirmed WAL receipt for those.
Author: Hou Zhijie and Shveta Malik
Reviewed-by: Masahiko Sawada, Peter Smith, Bertrand Drouvot, Ajin Cherian, Nisha Moond, Amit Kapila
Discussion: https://postgr.es/m/514f6f2f-6833-4539-39f1-96cd1e011f23@enterprisedb.com
This option can be used to switch a relation to use the access method
set by default_table_access_method when running the command.
This has come up when discussing the possibility to support setting
pg_class.relam for partitioned tables (left out here as future work),
while being useful on its own for relations with physical storage as
these must have an access method set.
Per suggestion from Justin Pryzby.
Author: Michael Paquier
Reviewed-by: Justin Pryzby
Discussion: https://postgr.es/m/ZeCZ89xAVFeOmrQC@pryzbyj2023
The copy_file_range() system call is available on at least Linux and
FreeBSD, and asks the kernel to use efficient ways to copy ranges of a
file. Options available to the kernel include sharing block ranges
(similar to --clone mode), and pushing down block copies to the storage
layer.
For automated testing, see PG_TEST_PG_UPGRADE_MODE. (Perhaps in a later
commit we could consider setting this mode for one of the CI targets.)
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Discussion: https://postgr.es/m/CA%2BhUKGKe7Hb0-UNih8VD5UNZy5-ojxFb3Pr3xSBBL8qj2M2%3DdQ%40mail.gmail.com
pg_constraint.conwithoutoverlaps was recently added to support primary
keys and unique constraints with the WITHOUT OVERLAPS clause. An
upcoming patch provides the foreign-key side of this functionality,
but the syntax there is different and uses the keyword PERIOD. It
would make sense to use the same pg_constraint field for both of
these, but then we should pick a more general name that conveys "this
constraint has a temporal/period-related feature". conperiod works
for that and is nicely compact. Changing this now avoids possibly
having to introduce versioning into clients. Note there are still
some "without overlaps" variables left, which deal specifically with
the parsing of the primary key/unique constraint feature.
Author: Paul A. Jungwirth <pj@illuminatedcomputing.com>
Discussion: https://www.postgresql.org/message-id/flat/CA+renyUApHgSZF9-nd-a0+OPGharLQLO=mDHcY4_qQ0+noCUVg@mail.gmail.com
Presently, if an archive module's check_configured_cb callback
returns false, a generic WARNING message is emitted, which
unfortunately provides no actionable details about the reason why
the module is not configured. This commit introduces a macro that
archive module authors can use to add a DETAIL line to this WARNING
message.
Co-authored-by: Tung Nguyen
Reviewed-by: Daniel Gustafsson, Álvaro Herrera
Discussion: https://postgr.es/m/4109578306242a7cd5661171647e11b2%40oss.nttdata.com
The adminpack extension was only used to support pgAdmin III, which
in turn was declared EOL many years ago. Removing the extension also
allows us to remove functions from core as well which were only used
to support old version of adminpack.
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Nathan Bossart <nathandbossart@gmail.com>
Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Discussion: https://postgr.es/m/CALj2ACUmL5TraYBUBqDZBi1C+Re8_=SekqGYqYprj_W8wygQ8w@mail.gmail.com
Commit 5f2e179bd3 missed one place in rules.sgml that should have
mentioned MERGE. Also, be more specific when saying that MERGE doesn't
support rules, since it does support SELECT rules.
The datatype for analyze_sampling had accidentally been set to text
and not string. Backpatch to v16 where analyze_sampling first was
introduced.
Author: Shinya Kato <Shinya11.Kato@oss.nttdata.com>
Reviewed-by: Laurenz Albe <laurenz.albe@cybertec.at>
Discussion: https://postgr.es/m/7fd9166b9fda267411793f39986d7f24@oss.nttdata.com
Backpatch-through: v16
Now that BackendId was just another index into the proc array, it was
redundant with the 0-based proc numbers used in other places. Replace
all usage of backend IDs with proc numbers.
The only place where the term "backend id" remains is in a few pgstat
functions that expose backend IDs at the SQL level. Those IDs are now
in fact 0-based ProcNumbers too, but the documentation still calls
them "backend ids". That term still seems appropriate to describe what
the numbers are, so I let it be.
One user-visible effect is that pg_temp_0 is now a valid temp schema
name, for backend with ProcNumber 0.
Reviewed-by: Andres Freund
Discussion: https://www.postgresql.org/message-id/8171f1aa-496f-46a6-afc3-c46fe7a9b407@iki.fi
Correct out-of-date text that said the "default" collation is always
based on LC_COLLATE and LC_CTYPE.
Also reformat into a list to make it easier to understand and compare
the available collations, and briefly document the stability
characteristics of each one.
Discussion: https://postgr.es/m/4a69d067374d2f6bfb66f5bfb2ab9a020493d49f.camel@j-davis.com
This allows the target relation of MERGE to be an auto-updatable or
trigger-updatable view, and includes support for WITH CHECK OPTION,
security barrier views, and security invoker views.
A trigger-updatable view must have INSTEAD OF triggers for every type
of action (INSERT, UPDATE, and DELETE) mentioned in the MERGE command.
An auto-updatable view must not have any INSTEAD OF triggers. Mixing
auto-update and trigger-update actions (i.e., having a partial set of
INSTEAD OF triggers) is not supported.
Rule-updatable views are also not supported, since there is no
rewriter support for non-SELECT rules with MERGE operations.
Dean Rasheed, reviewed by Jian He and Alvaro Herrera.
Discussion: https://postgr.es/m/CAEZATCVcB1g0nmxuEc-A+gGB0HnfcGQNGYH7gS=7rq0u0zOBXA@mail.gmail.com
More precisely, what we do here is make the SLRU cache sizes
configurable with new GUCs, so that sites with high concurrency and big
ranges of transactions in flight (resp. multixacts/subtransactions) can
benefit from bigger caches. In order for this to work with good
performance, two additional changes are made:
1. the cache is divided in "banks" (to borrow terminology from CPU
caches), and algorithms such as eviction buffer search only affect
one specific bank. This forestalls the problem that linear searching
for a specific buffer across the whole cache takes too long: we only
have to search the specific bank, whose size is small. This work is
authored by Andrey Borodin.
2. Change the locking regime for the SLRU banks, so that each bank uses
a separate LWLock. This allows for increased scalability. This work
is authored by Dilip Kumar. (A part of this was previously committed as
d172b717c6f4.)
Special care is taken so that the algorithms that can potentially
traverse more than one bank release one bank's lock before acquiring the
next. This should happen rarely, but particularly clog.c's group commit
feature needed code adjustment to cope with this. I (Álvaro) also added
lots of comments to make sure the design is sound.
The new GUCs match the names introduced by bcdfa5f2e2 in the
pg_stat_slru view.
The default values for these parameters are similar to the previous
sizes of each SLRU. commit_ts, clog and subtrans accept value 0, which
means to adjust by dividing shared_buffers by 512 (so 2MB for every 1GB
of shared_buffers), with a cap of 8MB. (A new slru.c function
SimpleLruAutotuneBuffers() was added to support this.) The cap was
previously 1MB for clog, so for sites with more than 512MB of shared
memory the total memory used increases, which is likely a good tradeoff.
However, other SLRUs (notably multixact ones) retain smaller sizes and
don't support a configured value of 0. These values based on
shared_buffers may need to be revisited, but that's an easy change.
There was some resistance to adding these new GUCs: it would be better
to adjust to memory pressure automatically somehow, for example by
stealing memory from shared_buffers (where the caches can grow and
shrink naturally). However, doing that seems to be a much larger
project and one which has made virtually no progress in several years,
and because this is such a pain point for so many users, here we take
the pragmatic approach.
Author: Andrey Borodin <x4mmm@yandex-team.ru>
Author: Dilip Kumar <dilipbalaut@gmail.com>
Reviewed-by: Amul Sul, Gilles Darold, Anastasia Lubennikova,
Ivan Lazarev, Robert Haas, Thomas Munro, Tomas Vondra,
Yura Sokolov, Васильев Дмитрий (Dmitry Vasiliev).
Discussion: https://postgr.es/m/2BEC2B3F-9B61-4C1D-9FB5-5FAB0F05EF86@yandex-team.ru
Discussion: https://postgr.es/m/CAFiTN-vzDvNz=ExGXz6gdyjtzGixKSqs0mKHMmaQ8sOSEFZ33A@mail.gmail.com
There isn't a lot of user demand for AIX support, we have a bunch of
hacks to work around AIX-specific compiler bugs and idiosyncrasies,
and no one has stepped up to the plate to properly maintain it.
Remove support for AIX to get rid of that maintenance overhead. It's
still supported for stable versions.
The acute issue that triggered this decision was that after commit
8af2565248, the AIX buildfarm members have been hitting this
assertion:
TRAP: failed Assert("(uintptr_t) buffer == TYPEALIGN(PG_IO_ALIGN_SIZE, buffer)"), File: "md.c", Line: 472, PID: 2949728
Apperently the "pg_attribute_aligned(a)" attribute doesn't work on AIX
for values larger than PG_IO_ALIGN_SIZE, for a static const variable.
That could be worked around, but we decided to just drop the AIX support
instead.
Discussion: https://www.postgresql.org/message-id/20240224172345.32@rfd.leadboat.com
Reviewed-by: Andres Freund, Noah Misch, Thomas Munro
The new names are intended to match those in an upcoming patch that adds
a few GUCs to configure the SLRU buffer sizes.
Backwards compatibility concern: this changes the accepted names for
function pg_stat_slru_rest(). Since this function recognizes "any other
string" as a request to reset the entry for "other", this means that
calling it with the old names would silently reset "other" instead of
doing nothing or throwing an error.
Reviewed-by: Andrey M. Borodin <x4mmm@yandex-team.ru>
Discussion: https://postgr.es/m/202402261616.dlriae7b6emv@alvherre.pgsql
Add a note about the additional privileges required after the fix in
4989ce7264 (wording per Tom Lane); also change marked-up mentions of
"target_table_name" to be simply "the target table" or the like. Also,
note that "join_condition" is scouted for requisite privileges.
Backpatch to 15.
Discussion: https://postgr.es/m/202402211653.zuh6objy3z72@alvherre.pgsql
By enabling slot synchronization, all the failover logical replication
slots on the primary (assuming configurations are appropriate) are
automatically created on the physical standbys and are synced
periodically. The slot sync worker on the standby server pings the primary
server at regular intervals to get the necessary failover logical slots
information and create/update the slots locally. The slots that no longer
require synchronization are automatically dropped by the worker.
The nap time of the worker is tuned according to the activity on the
primary. The slot sync worker waits for some time before the next
synchronization, with the duration varying based on whether any slots were
updated during the last cycle.
A new parameter sync_replication_slots enables or disables this new
process.
On promotion, the slot sync worker is shut down by the startup process to
drop any temporary slots acquired by the slot sync worker and to prevent
the worker from trying to fetch the failover slots.
A functionality to allow logical walsenders to wait for the physical will
be done in a subsequent commit.
Author: Shveta Malik, Hou Zhijie based on design inputs by Masahiko Sawada and Amit Kapila
Reviewed-by: Masahiko Sawada, Bertrand Drouvot, Peter Smith, Dilip Kumar, Ajin Cherian, Nisha Moond, Kuroda Hayato, Amit Kapila
Discussion: https://postgr.es/m/514f6f2f-6833-4539-39f1-96cd1e011f23@enterprisedb.com
The explanation of interval's behavior in datatype.sgml wasn't wrong
exactly, but it was unclear, partly because it buried the lede about
there being three internal fields. Rearrange and wordsmith for more
clarity.
The discussion of extract() claimed that input of type date was
handled by casting, but actually there's been a separate SQL function
taking date for a very long time. Also, it was mostly silent about
how interval inputs are handled, but there are several field types
for which it seems useful to be specific.
Improve discussion of justify_days()/justify_hours() too.
In passing, remove vertical space in some groups of examples,
as there was little consistency about whether to have such space
or not. (I only did this within the datetime functions section;
there are some related inconsistencies elsewhere.)
Per discussion of bug #18348 from Michael Bondarenko. There
may be some code changes coming out of that discussion too,
but we likely won't back-patch them. This docs-only patch
seems useful to back-patch, though I only carried it back to
v13 because it didn't apply easily in v12.
Discussion: https://postgr.es/m/18348-b097a3587dfde8a4@postgresql.org
Alvaro Herrera