Backpatch to 9.3

Adjusted patch from Ian Lawrence Barwick

Commit 820f08ca claimed to make the server
and libpq handle SSL protocol versions identically, but actually the server
was still accepting SSL v3 protocol while libpq wasn't.  Per discussion,
SSL v3 is obsolete, and there's no good reason to continue to accept it.
So make the code really equivalent on both sides.  The behavior now is
that we use the highest mutually-supported TLS protocol version.

Marko Kreen, some comment-smithing by me

Dean Rasheed

Michael Paquier

Suggested by David Tonhofer

Document that FOR UPDATE/SHARE are incompatible with GROUP BY, DISTINCT,
HAVING and window functions.

Michael Paquier

Report form Antonin Houska

Allows typedefs to be specified on the command line, per request from
Andrew.

Add new entab options to process only C comment whitespace after
periods, and to protect leading whitespace.

Per gripe from hubert depesz lubaczewski.

Also improve examples for this and json_array_elements so they match the
example results.

The buildfarm says commit 58274728 doesn't
work so well on Windows.  This is because the encoding part of Windows
locale names can be just a code page number, eg "1252", which we don't
consider to be a valid encoding name.  Add a check to accept encoding
parts that are case-insensitively string equal; this at least ensures
that the new code doesn't reject any cases that the old code allowed.

This requires a new version of pg_bsd_indent, version 1.3, to be
downloaded.

Even though the server tries to canonicalize stored locale names, the
platform often doesn't cooperate, so it's entirely possible that one DB
thinks its locale is, say, "en_US.UTF-8" while the other has "en_US.utf8".
Rather than failing, we should try to allow this where it's clearly OK.

There is already pretty robust encoding lookup in encnames.c, so make
use of that to compare the encoding parts of the names.  The locale
identifier parts are just compared case-insensitively, which we were
already doing.  The major problem known to exist in the field is variant
encoding-name spellings, so hopefully this will be Good Enough.  If not,
we can try being even laxer.

Pavel Raiskup, reviewed by Rushabh Lathia

Thinko in error report (and a typo in the message text, too).  We're
failing anyway, but it would be good to print something useful first.
Noted while reviewing a patch to make pg_upgrade's locale code laxer.

Vik Fearing, reviewed by Pavel Stehule and myself

When pulling a "postponed" qual from a LATERAL subquery up into the quals
of an outer join, we must make sure that the postponed qual is included
in those seen by make_outerjoininfo().  Otherwise we might compute a
too-small min_lefthand or min_righthand for the outer join, leading to
"JOIN qualification cannot refer to other relations" failures from
distribute_qual_to_rels.  Subtler errors in the created plan seem possible,
too, if the extra qual would only affect join ordering constraints.

Per bug #9041 from David Leverton.  Back-patch to 9.3.

Backpatch to 9.3

Greg Smith

New checks include input, month/day/time internal adjustments, addition,
subtraction, multiplication, and negation.  Also adjust docs to
correctly specify interval size in bytes.

Report from Rok Kralj

Various places were supposing that errno could be expected to hold still
within an ereport() nest or similar contexts.  This isn't true necessarily,
though in some cases it accidentally failed to fail depending on how the
compiler chanced to order the subexpressions.  This class of thinko
explains recent reports of odd failures on clang-built versions, typically
missing or inappropriate HINT fields in messages.

Problem identified by Christian Kruse, who also submitted the patch this
commit is based on.  (I fixed a few issues in his patch and found a couple
of additional places with the same disease.)

Back-patch as appropriate to all supported branches.

They are in fact set in every case where they are needed, but the
compiler doesn't know that.

Per gripe from Tom Lane.

This doesn't work for prepared queries, but it's not too easy to get
the information in that case and there's some debate as to exactly
what the right thing to measure is, so just do this for now.

Andreas Karlsson, with slight doc changes by me.

This was a notable omission from the json functions added in 9.3 and
there have been numerous complaints about its absence.

Laurence Rowe.

We calculated the rounded-up size for the allocation, but then failed to
use the rounded-up value in the mmap() call. Oops.

Also, initialize allocsize, to silence warnings seen with some compilers,
as pointed out by Jeff Janes.

When skipping over some items in a posting tree, re-find the new location
by descending the tree from root, rather than walking the right links.
This can save a lot of I/O.

Heavily modified from Alexander Korotkov's fast scan patch.

If we're skipping past a certain TID, avoid decoding posting list segments
that only contain smaller TIDs.

Extracted from Alexander Korotkov's fast scan patch, heavily modified.

In a multi-key search, ie. something like "col @> 'foo' AND col @> 'bar'",
as soon as we find the next item that matches the first criteria, we don't
need to check the second criteria for TIDs smaller the first match. That
saves a lot of effort, especially if one of the terms is rare, while the
second occurs very frequently.

Based on ideas from Alexander Korotkov's fast scan patch.

Broken by the huge_tlb_pages patch.

Vik Fearing.

This patch adds an option, huge_tlb_pages, which allows requesting the
shared memory segment to be allocated using huge pages, by using the
MAP_HUGETLB flag in mmap(). This can improve performance.

The default is 'try', which means that we will attempt using huge pages,
and fall back to non-huge pages if it doesn't work. Currently, only Linux
has MAP_HUGETLB. On other platforms, the default 'try' behaves the same as
'off'.

In the passing, don't try to round the mmap() size to a multiple of
pagesize. mmap() doesn't require that, and there's no particular reason for
PostgreSQL to do that either. When using MAP_HUGETLB, however, round the
request size up to nearest 2MB boundary. This is to work around a bug in
some Linux kernel versions, but also to avoid wasting memory, because the
kernel will round the size up anyway.

Many people were involved in writing this patch, including Christian Kruse,
Richard Poole, Abhijit Menon-Sen, reviewed by Peter Geoghegan, Andres Freund
and me.

Per a report by Rajeev Rastogi.

Thom Brown.

These do not run any specific schedule of tests, but only those
specified as part of the invocation, e.g.:

    make check-tests TESTS="json jsonb"