Coverity noted that the last line of gather_merge_getnext() was
unreachable, since each arm of the preceding "if" ends in a "return".
Drop it as an oversight.  In passing, improve some nearby comments.

Upcoming patches are revamping expression evaluation significantly. It
therefore seems prudent to try to ensure that the coverage of the
existing evaluation code is high.

This commit adds coverage for the cases that can reasonably be
tested. There's still a bunch of unreachable error messages and such,
but otherwise this achieves nearly full regression test coverage (with
the exception of the unused GetAttributeByNum/GetAttributeByName).

Author: Andres Freund
Discussion: https://postgr.es/m/20170310194021.ek4bs4bl2khxkmll@alap3.anarazel.de

When using unnamed connections with dblink, every time a new
connection is made, the old one is leaked. Fix that.

This has been an issue probably since dblink was first committed.
Someone complained almost ten years ago, but apparently I decided
not to pursue it at the time, and neither did anyone else, so it
slipped between the cracks. Now that someone else has complained,
fix in all supported branches.

Discussion: (orig) https://postgr.es/m/flat/F680AB59-6D6F-4026-9599-1BE28880273D%40decibel.org#F680AB59-6D6F-4026-9599-1BE28880273D@decibel.org
Discussion: (new) https://postgr.es/m/flat/0A3221C70F24FB45833433255569204D1F6ADF8C@G01JPEXMBYT05
Reported by: Jim Nasby and Takayuki Tsunakawa

This allows rolling back the effects of some SPI commands without
having to fail the entire PL/Tcl function.

Victor Wagner, reviewed by Pavel Stehule

Discussion: https://postgr.es/m/20170108205750.2dab04a1@wagner.wagner.home

When one of the kernel calls in the socket()/bind()/listen() sequence
fails, include the specific address we're trying to bind to in the log
message.  This greatly eases debugging of network misconfigurations.

Also, after successfully setting up a listen socket, report its address
in the log, to ease verification that the expected addresses were bound.
There was some debate about whether to print this message at LOG level or
only DEBUG1, but the majority of votes were for the former.

Discussion: https://postgr.es/m/9564.1489091245@sss.pgh.pa.us

Dumping a publication with more than one table crashed pg_dump.

patch by Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>, test by me

There's no really good reason why the autovacuum launcher and logical
replication launcher should announce themselves at startup and shutdown
by default.  Users don't care that those processes exist, and it's
inconsistent that those background processes announce themselves while
others don't.  So, reduce those messages from LOG to DEBUG1 level.

I was sorely tempted to reduce the "starting logical replication worker
for subscription ..." message to DEBUG1 as well, but forebore for now.
Those processes might possibly be of direct interest to users, at least
until logical replication is a lot better shaken out than it is today.

Discussion: https://postgr.es/m/19479.1489121003@sss.pgh.pa.us

This reverts commit ccce90b3.  This
optimization is unsafe, at least, of rollbacks and rollbacks to
savepoints, but I'm concerned there may be other problematic cases as
well.  Therefore, I've decided to revert this pending further
investigation.

Previously they were disabled due to performance concerns on 32bit
arm, where 64bit atomics are often implemented via kernel traps.

Author: Roman Shaposhnik
Discussion: http://postgr.es/m/CA+ULb+uErkFuXUCCXWHYvnV5KnAyjGUzzRcPA-M0cgO+Hm4RSA@mail.gmail.com

Commits 89e0bac8 et al replaced newlines with spaces in object names
printed in SQL comments, but we neglected to consider that the same
names are also printed by "pg_restore -l", and a newline would render
the output unparseable by "pg_restore -L".  Apply the same replacement
in "-l" output.  Since "pg_restore -L" doesn't actually examine any
object names, only the dump ID field that starts each line, this is
enough to fix things for its purposes.

The previous fix was treated as a security issue, and we might have
done that here as well, except that the issue was reported publicly
to start with.  Anyway it's hard to see how this could be exploited
for SQL injection; "pg_restore -L" doesn't do much with the file
except parse it for leading integers.

Per bug #14587 from Milos Urbanek.  Back-patch to all supported versions.

Discussion: https://postgr.es/m/20170310155318.1425.30483@wrigleys.postgresql.org

Seven of the eight other relkind codes are lower-case, so it wasn't
consistent for this one to be upper-case.  Fix it while we still can.

Historical notes: the reason for the lone exception, i.e. sequences being
'S', is that 's' was once used for "special" relations.  Also, at one time
the partitioned-tables patch used both 'P' and 'p', but that got changed,
leaving only a surprising choice behind.

This also fixes a couple little bits of technical debt, such as
type_sanity.sql not knowing that 'm' is a legal value for relkind.

Discussion: https://postgr.es/m/27899.1488909319@sss.pgh.pa.us

Commit be37c212 forgot to teach initdb about commenting out the IPv6
replication entry that it caused to exist in pg_hba.conf.sample.
Per buildfarm.

One file was listed under a wrong comment.

For consistency with other code and to avoid wasting some small amount
of memory.

From: Tsunakawa, Takayuki <tsunakawa.takay@jp.fujitsu.com>

Also remove some unused code and the no longer useful dblink.h file.
Reviewed-by: Tsunakawa, Takayuki <tsunakawa.takay@jp.fujitsu.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.

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