Although it's reasonable to expect that most of these constants will
never change, that does not make it good programming style to hard-code
the value rather than using the RELKIND_FOO macros.

I think I've now gotten all the hard-coded references in C code.
Unfortunately there's no equally convenient way to parameterize
SQL files ...

Discussion: https://postgr.es/m/11145.1488931324@sss.pgh.pa.us

No exclusive lock is taken anymore...

Per buildfarm.  Maybe some of the other xmin variables in snapmgr.h
ought to get this too, but for the moment I'm just interested in
un-breaking the buildfarm.

Oversight in commit 3717dc14.

Although it's reasonable to expect that most of these constants will
never change, that does not make it good programming style to hard-code
the value rather than using the RELKIND_FOO macros.

Discussion: https://postgr.es/m/11145.1488931324@sss.pgh.pa.us

Commit 7666e73a introduced a dependency on filehandles' input_line_number
method, but apparently that's a Perl neologism.  Use $. instead, which
works at least back to Perl 5.10, and hopefully back to 5.8.

Jeff Janes

Discussion: https://postgr.es/m/CAMkU=1wuQW=xVfu-14A4VCvxO0ohkD3m9vk6HOj_dprQoKNAQw@mail.gmail.com

Although it's reasonable to expect that most of these constants will
never change, that does not make it good programming style to hard-code
the value rather than using the RELKIND_FOO macros.

Discussion: https://postgr.es/m/11145.1488931324@sss.pgh.pa.us

Pointed out by Michael Paquier

This is the beginning of a collection of SQL-callable functions to
verify the integrity of data files.  For now it only contains code to
verify B-Tree indexes.

This adds two SQL-callable functions, validating B-Tree consistency to
a varying degree.  Check the, extensive, docs for details.

The goal is to later extend the coverage of the module to further
access methods, possibly including the heap.  Once checks for
additional access methods exist, we'll likely add some "dispatch"
functions that cover multiple access methods.

Author: Peter Geoghegan, editorialized by Andres Freund
Reviewed-By: Andres Freund, Tomas Vondra, Thomas Munro,
   Anastasia Lubennikova, Robert Haas, Amit Langote
Discussion: CAM3SWZQzLMhMwmBqjzK+pRKXrNUZ4w90wYMUWfkeV8mZ3Debvw@mail.gmail.com

Although it's reasonable to expect that most of these constants will
never change, that does not make it good programming style to hard-code
the value rather than using the RELKIND_FOO macros.  There were only
a few such violations, and all relatively new AFAICT.

Existing style is mostly to inject relkind values into constructed
query strings using %c.  I did not bother to touch places that did it
like that, but really a better technique is to stringify the RELKIND
macro, at least in places where you'd want single quotes around the
code character.  That avoids any runtime effort and keeps the RELKIND
symbol close to where it's used.

Discussion: https://postgr.es/m/11145.1488931324@sss.pgh.pa.us

For some reason this standard C string-processing hack was buried in an
NLS-related section of c.h.  Put it beside CppAsString() so that people
are more likely to find it and not be tempted to reinvent local copies,
as I nearly did.  And provide a more helpful comment, too.

David Christensen, reviewed by Dagfinn Ilmari Mannsåker

Discussion: http://postgr.es/m/20170215154018.fs5vwtqhp5d2sifs@veeddeux.attlocal.net

Commit 0e141c0f introduced a mechanism
to reduce contention on ProcArrayLock by having a single process clear
XIDs in the procArray on behalf of multiple processes, reducing the
need to hand the lock around.  Use a similar mechanism to reduce
contention on CLogControlLock.  Testing shows that this very
significantly reduces the amount of time waiting for CLogControlLock
on high-concurrency pgbench tests run on a large multi-socket
machines; whether that translates into a TPS improvement depends on
how much of that contention is simply shifted to some other lock,
particularly WALWriteLock.

Amit Kapila, with some cosmetic changes by me.  Extensively reviewed,
tested, and benchmarked over a period of about 15 months by Simon
Riggs, Robert Haas, Andres Freund, Jesper Pedersen, and especially by
Tomas Vondra and Dilip Kumar.

Discussion: http://postgr.es/m/CAA4eK1L_snxM_JcrzEstNq9P66++F4kKFce=1r5+D1vzPofdtg@mail.gmail.com
Discussion: http://postgr.es/m/CAA4eK1LyR2A+m=RBSZ6rcPEwJ=rVi1ADPSndXHZdjn56yqO6Vg@mail.gmail.com
Discussion: http://postgr.es/m/91d57161-d3ea-0cc2-6066-80713e4f90d7@2ndquadrant.com

The IANA timezone crew continues to chip away at their project of removing
timezone abbreviations that have no real-world currency from their
database.  The tzdata2017a update removes all such abbreviations for
South American zones, as well as much of the Pacific.  This breaks some
test cases in timestamptz.sql that were expecting America/Santiago and
America/Caracas to have non-numeric abbreviations.

The test cases involving America/Santiago seem to have selected that
zone more or less at random, so just replace it with America/New_York,
which is of similar longitude.  The cases involving America/Caracas are
harder since they were chosen to test a time-varying zone abbreviation
around a point where it changed meaning in the backwards direction.
Fortunately, Europe/Moscow has a similar case in 2014, and the MSK/MSD
abbreviations are well enough attested that IANA seems unlikely to
decide to remove them from the database in future.

With these changes, this regression test should pass when using any IANA
zone database from 2015 or later.  One could wish that there were a few
years more daylight on how out-of-date your zone database can be ... but
really the --with-system-tzdata option is only meant for use on platforms
where the zone database is kept up-to-date pretty faithfully, so I do not
think this is a big objection.

Discussion: https://postgr.es/m/6749.1489087470@sss.pgh.pa.us

The contrib extensions pageinspect, pg_visibility and pgstattuple only
work against regular relations which have storage.  They don't work
against foreign tables, partitioned (parent) tables, views, et al.

Add checks to the user-callable functions to return a useful error
message to the user if they mistakenly pass an invalid relation to a
function which doesn't accept that kind of relation.

In passing, improve some of the existing checks to use ereport() instead
of elog(), add a function to consolidate common checks where
appropriate, and add some regression tests.

Author: Amit Langote, with various changes by me
Reviewed by: Michael Paquier and Corey Huinker
Discussion: https://postgr.es/m/ab91fd9d-4751-ee77-c87b-4dd704c1e59c@lab.ntt.co.jp

Ashutosh Bapat, revised a bit by me.

Discussion: http://postgr.es/m/CAFjFpRdLaCa-1wJase0=YWG5o3cJnbuUt_vrqm2TDBKM_vQ_oA@mail.gmail.com

This updates the text for parallel index scan, parallel index-only
scan, parallel bitmap heap scan, and parallel merge join.  It also
expands the discussion of parallel joins slightly.

Discussion: http://postgr.es/m/CA+TgmoZnCUoM31w3w7JSakVQJQOtcuTyX=HLUr-X1rto2=2bjw@mail.gmail.com

Avoid computing idxpages[istate->spageptr] until after checking
that istate->spageptr is a legal index.

Dilip Kumar, per a report from David Rowley

Discussion: http://postgr.es/m/CAKJS1f8OtrHE+-P+=E=4ycnL29e9idZKuaTQ6o2MbhvGN9D8ig@mail.gmail.com

Neha Sharma reported these to Rushabh Lathia just after I commit
355d3993 went in.  The patch is
Rushabh's, with input from me.

initdb now initializes a pg_hba.conf that allows replication connections
from the local host, same as it does for regular connections.  The
connecting user still needs to have the REPLICATION attribute or be a
superuser.

The intent is to allow pg_basebackup from the local host to succeed
without requiring additional configuration.

Michael Paquier <michael.paquier@gmail.com> and me

Like Gather, we spawn multiple workers and run the same plan in each
one; however, Gather Merge is used when each worker produces the same
output ordering and we want to preserve that output ordering while
merging together the streams of tuples from various workers.  (In a
way, Gather Merge is like a hybrid of Gather and MergeAppend.)

This works out to a win if it saves us from having to perform an
expensive Sort.  In cases where only a small amount of data would need
to be sorted, it may actually be faster to use a regular Gather node
and then sort the results afterward, because Gather Merge sometimes
needs to wait synchronously for tuples whereas a pure Gather generally
doesn't.  But if this avoids an expensive sort then it's a win.

Rushabh Lathia, reviewed and tested by Amit Kapila, Thomas Munro,
and Neha Sharma, and reviewed and revised by me.

Discussion: http://postgr.es/m/CAGPqQf09oPX-cQRpBKS0Gq49Z+m6KBxgxd_p9gX8CKk_d75HoQ@mail.gmail.com

We have a project policy that every .c file should start by including
postgres.h, postgres_fe.h, or c.h as appropriate; and then there is no
need for any .h file to explicitly include any of these.  Fix a few
headers that were violating this policy by including c.h.

Discussion: https://postgr.es/m/CAEepm=2zCoeq3QxVwhS5DFeUh=yU6z81pbWMgfOB8OzyiBwxzw@mail.gmail.com
Discussion: https://postgr.es/m/11634.1488932128@sss.pgh.pa.us

We have a project policy that every .c file should start by including
postgres.h, postgres_fe.h, or c.h as appropriate; and then there is no
need for any .h file to explicitly include any of these.  Fix a few
headers that were violating this policy by including postgres_fe.h.

Discussion: https://postgr.es/m/CAEepm=2zCoeq3QxVwhS5DFeUh=yU6z81pbWMgfOB8OzyiBwxzw@mail.gmail.com
Discussion: https://postgr.es/m/11634.1488932128@sss.pgh.pa.us

We have a project policy that every .c file should start by including
postgres.h, postgres_fe.h, or c.h as appropriate; and then there is no
need for any .h file to explicitly include any of these.  (The core
reason for this policy is to make it easy to verify that pg_config_os.h
is included before any system headers such as <stdio.h>; without that,
we have portability issues on some platforms due to variation in largefile
options across different modules in the backend.  Also, if .h files were
responsible for choosing which of these key headers to include, .h files
that need to be includable in either frontend or backend compiles would be
in trouble.)

plpgsql was blithely ignoring this policy, so whack it upside the head
until it complies.  I also chose to standardize on including plpgsql's
own .h files after all core-system headers that it pulls in.  That
could've been done either way, but this way seems saner.

Discussion: https://postgr.es/m/CAEepm=2zCoeq3QxVwhS5DFeUh=yU6z81pbWMgfOB8OzyiBwxzw@mail.gmail.com
Discussion: https://postgr.es/m/11634.1488932128@sss.pgh.pa.us

Although there are good reasons for our policy of including postgres.h
as the first #include in every .c file, never from .h files, there are
two places where it seems expedient to violate the policy because the
alternative is to modify externally-supplied .c files.  (In the case
of the regexp library, the idea that it's externally-supplied is kind
of at odds with reality, but I haven't entirely given up hope that it
will become a standalone project some day.)  Add some comments to make
it explicit that this is a policy violation and provide the reasoning.

In passing, move #include "miscadmin.h" out of regcomp.c and into
regcustom.h, which is where it should be if we're taking this reasoning
seriously at all.

Discussion: https://postgr.es/m/CAEepm=2zCoeq3QxVwhS5DFeUh=yU6z81pbWMgfOB8OzyiBwxzw@mail.gmail.com
Discussion: https://postgr.es/m/11634.1488932128@sss.pgh.pa.us

Compilers that don't realize that elog(ERROR) doesn't return
complained that SlabRealloc() failed to return a value.

While at it, fix the rather muddled header comment for the function.

Per buildfarm.

Compilers that don't realize that ereport(ERROR) doesn't return
complained that XmlTableGetValue() failed to return a value.

Also, make XmlTableFetchRow's non-USE_LIBXML case look more like
the other ones.  As coded, it could lead to "unreachable code"
warnings with USE_LIBXML enabled.

Oversights in commit fcec6caa.  Per buildfarm.

Further fallout from commit c29aff95: there are some files that need
<float.h>, and were getting it from datatype/timestamp.h, but it was not
apparent in my (tgl's) testing because the requirement for <float.h>
exists only on certain Windows toolchains.

Report and patch by David Rowley.

Discussion: https://postgr.es/m/CAKJS1f-BHceaFzZScFapDV48gUVM2CAOBfhkgffdqXzFb+kwew@mail.gmail.com

This exposes the existing explain summary option to users to allow them
to choose if they wish to have the planning time and totalled run time
included in the EXPLAIN result.  The existing default behavior is
retained if SUMMARY is not specified- running explain without analyze
will not print the summary lines (just the planning time, currently)
while running explain with analyze will include the summary lines (both
the planning time and the totalled execution time).

Users who wish to see the summary information for plain explain can now
use: EXPLAIN (SUMMARY ON) query;  Users who do not want to have the
summary printed for an analyze run can use:
EXPLAIN (ANALYZE ON, SUMMARY OFF) query;

With this, we can now also have EXPLAIN ANALYZE queries included in our
regression tests by using:
EXPLAIN (ANALYZE ON, TIMING OFF, SUMMARY off) query;

I went ahead and added an example of this, which will hopefully not make
the buildfarm complain.

Author: Ashutosh Bapat
Discussion: https://postgr.es/m/CAFjFpReE5z2h98U2Vuia8hcEkpRRwrauRjHmyE44hNv8-xk+XA@mail.gmail.com

Same disease as 270d7dd8.

Large chunks (those too large for any palloc freelist) are managed as
separate blocks.  Formerly, realloc'ing or pfree'ing such a chunk required
O(N) time in a context with N blocks, since we had to traipse down the
singly-linked block list to locate the block's predecessor before we could
fix the list links.  This can result in O(N^2) runtime in situations where
large numbers of such chunks are manipulated within one context.  Cases
like that were not foreseen in the original design of aset.c, and indeed
didn't arise until fairly recently.  But such problems can now occur in
reorderbuffer.c and in hash joining, both of which make repeated large
requests without scaling up their request size as they do so, and which
will free their requests in not-necessarily-LIFO order.

To fix, change the block list from singly-linked to doubly-linked.
This adds another 4 or 8 bytes to ALLOC_BLOCKHDRSZ, but that doesn't
seem like unacceptable overhead, since aset.c's blocks are normally
8K or more, and never less than 1K in current practice.

In passing, get rid of some redundant AllocChunkGetPointer() calls in
AllocSetRealloc (the compiler might be smart enough to optimize these
away anyway, but no need to assume that) and improve AllocSetCheck's
checking of block header fields.

Back-patch to 9.4 where reorderbuffer.c appeared.  We could take this
further back, but currently there's no evidence that it would be useful.

Discussion: https://postgr.es/m/CAMkU=1x1hvue1XYrZoWk_omG0Ja5nBvTdvgrOeVkkeqs71CV8g@mail.gmail.com

The index is scanned by a single process, but then all cooperating
processes can iterate jointly over the resulting set of heap blocks.
In the future, we might also want to support using a parallel bitmap
index scan to set up for a parallel bitmap heap scan, but that's a
job for another day.

Dilip Kumar, with some corrections and cosmetic changes by me.  The
larger patch set of which this is a part has been reviewed and tested
by (at least) Andres Freund, Amit Khandekar, Tushar Ahuja, Rafia
Sabih, Haribabu Kommi, Thomas Munro, and me.

Discussion: http://postgr.es/m/CAFiTN-uc4=0WxRGfCzs-xfkMYcSEWUC-Fon6thkJGjkh9i=13A@mail.gmail.com

Any logical rep workers must have their subscription entries in
pg_subscription. To ensure this, we need to prevent the launcher
from starting new worker corresponding to the subscription that
DROP SUBSCRIPTION command is removing. To implement this,
previously LogicalRepLauncherLock was introduced and held until
the end of transaction running DROP SUBSCRIPTION. But using
LWLock for that purpose was not valid.

Instead, this commit changes DROP SUBSCRIPTION so that it takes
AccessExclusiveLock on pg_subscription, in order to ensure that
the launcher cannot see any subscriptions being removed. Also this
commit gets rid of LogicalRepLauncherLock.

Patch by me, reviewed by Petr Jelinek

Discussion: https://www.postgresql.org/message-id/CAHGQGwHPi8ky-yANFfe0sgmhKtsYcQLTnKx07bW9S7-Rn1746w@mail.gmail.com

libxml2 older than 2.9.1 does not have xmlXPathSetContextNode (released
in 2013, so reasonable platforms have trouble).  That function is fairly
trivial, so I have inlined it in the one added caller.  This passes
tests on my machine; let's see what the buildfarm thinks about it.

Per joint complaint from Tom Lane and buildfarm.

Amit Langote, reviewed by Ashutosh Bapat

Discussion: http://postgr.es/m/475dd52c-be4a-9b32-6d54-3044a00c93d9@lab.ntt.co.jp

XMLTABLE is defined by the SQL/XML standard as a feature that allows
turning XML-formatted data into relational form, so that it can be used
as a <table primary> in the FROM clause of a query.

This new construct provides significant simplicity and performance
benefit for XML data processing; what in a client-side custom
implementation was reported to take 20 minutes can be executed in 400ms
using XMLTABLE.  (The same functionality was said to take 10 seconds
using nested PostgreSQL XPath function calls, and 5 seconds using
XMLReader under PL/Python).

The implemented syntax deviates slightly from what the standard
requires.  First, the standard indicates that the PASSING clause is
optional and that multiple XML input documents may be given to it; we
make it mandatory and accept a single document only.  Second, we don't
currently support a default namespace to be specified.

This implementation relies on a new executor node based on a hardcoded
method table.  (Because the grammar is fixed, there is no extensibility
in the current approach; further constructs can be implemented on top of
this such as JSON_TABLE, but they require changes to core code.)

Author: Pavel Stehule, Álvaro Herrera
Extensively reviewed by: Craig Ringer
Discussion: https://postgr.es/m/CAFj8pRAgfzMD-LoSmnMGybD0WsEznLHWap8DO79+-GTRAPR4qA@mail.gmail.com

Maybe Robert's compiler can convince itself that these variables are
never used uninitialized, but mine can't.

fatal_error() already prints out a trailing newline.