Author: Daniel Gustafsson

Commit 65abaab5 tried to prevent the scaling constants used in
the degree-based trig functions from being precomputed at compile time,
because some compilers do that with functions that don't yield results
identical-to-the-last-bit to what you get at runtime.  A report from
Peter Eisentraut suggests that some recent compilers are smart enough
to see through that trick, though.  Instead, let's put the inputs to
these calculations into non-const global variables, which should be a
more reliable way of convincing the compiler that it can't assume that
they are compile-time constants.  (If we really get desperate, we could
mark these variables "volatile", but I do not believe we should have to.)

Commit fab84c77 tried to get away without doing an actual bind(),
but buildfarm results show that that doesn't get the job done.  So we must
really bind to the target port --- and at least on my Linux box, we need a
listen() as well, or conflicts won't be detected.  We rely on SO_REUSEADDR
to prevent problems from starting a postmaster on the socket immediately
after we've bound to it in the test code.  (There may be platforms where
that doesn't work too well.  But fortunately, we only really care whether
this works on Windows, and there the default behavior should be OK.)

From: Andreas Seltenreich <andreas.seltenreich@credativ.de>

Buildfarm members bowerbird and jacana have shown intermittent "could not
bind IPv4 socket" failures in the BinInstallCheck stage since mid-December,
shortly after commits 1caef31d and 9821492e changed the
logic for selecting which port to use in temporary installations.  One
plausible explanation is that we are randomly selecting ports that are
already in use for some non-Postgres purpose.  Although the code tried
to defend against already-in-use ports, it used pg_isready to probe
the port which is quite unhelpful: if some non-Postgres server responds
at the given address, pg_isready will generally say "no response",
leading to exactly the wrong conclusion about whether the port is free.

Instead, let's use a simple TCP connect() call to see if anything answers
without making assumptions about what it is.  Note that this means there's
no direct check for a conflicting Unix socket, but that should be okay
because there should be no other Unix sockets in use in the temporary
socket directory created for a test run.

This is only a partial solution for the TCP case, since if the port number
is in use for an outgoing connection rather than a listening socket, we'll
fail to detect that.  We could try to bind() to the proposed port as a
means of detecting that case, but that would introduce its own failure
modes, since the system might consider the address to remain reserved for
some period of time after we drop the bound socket.  Close study of the
errors returned by bowerbird and jacana suggests that what we're seeing
there may be conflicts with listening not outgoing sockets, so let's try
this and see if it improves matters.  It's certainly better than what's
there now, in any case.

Michael Paquier, adjusted by me to work on non-Windows as well as Windows

Several issues:
1) checkpoint_flush_after doc and code disagreed about the default
2) new GUCs were missing from postgresql.conf.sample
3) Outdated source-code comment about bgwriter_flush_after's default
4) Sub-optimal categories assigned to new GUCs
5) Docs suggested backend_flush_after is PGC_SIGHUP, but it's PGC_USERSET.
6) Spell out int as integer in the docs, as done elsewhere

Reported-By: Magnus Hagander, Fujii Masao
Discussion: CAHGQGwETyTG5VYQQ5C_srwxWX7RXvFcD3dKROhvAWWhoSBdmZw@mail.gmail.com

NetBSD has seen fit to invent a libc function named strtoi(), which
conflicts with the long-established static functions of the same name in
datetime.c and ecpg's interval.c.  While muttering darkly about intrusions
on application namespace, we'll rename our functions to avoid the conflict.

Back-patch to all supported branches, since this would affect attempts
to build any of them on recent NetBSD.

Thomas Munro

From: Erik Rijkers <er@xs4all.nl>

Was part of box type in SP-GiST index patch.

Reported-by: Emre Hasegeli

It appears that we can no longer get away with using V0 call convention
for bool-returning functions in newer versions of MSVC.  The compiler
seems to generate code that doesn't clear the higher-order bits of the
result register, causing the bool result Datum to often read as "true"
when "false" was intended.  This is not very surprising, since the
function thinks it's returning a bool-width result but fmgr_oldstyle
assumes that V0 functions return "char *"; what's surprising is that
that hack worked for so long on so many platforms.

The only functions of this description in core+contrib are in contrib/seg,
which we'd intentionally left mostly in V0 style to serve as a warning
canary if V0 call convention breaks.  We could imagine hacking things
so that they're still V0 (we'd have to redeclare the bool-returning
functions as returning some suitably wide integer type, like size_t,
at the C level).  But on the whole it seems better to convert 'em to V1.
We can still leave the pointer- and int-returning functions in V0 style,
so that the test coverage isn't gone entirely.

Back-patch to 9.5, since our intention is to support VS2015 in 9.5
and later.  There's no SQL-level change in the functions' behavior
so back-patching should be safe enough.

Discussion: <22094.1461273324@sss.pgh.pa.us>

Michael Paquier, adjusted some by me

This was missed when VS 2013 support was added.

Michael Paquier

The implementation of that feature involves injecting nodes into the
raw parsetree where explicit parentheses appear.  Various places in
parse_expr.c that test to see "is this child node of type Foo" need to
look through such nodes, else we'll get different behavior when
operator_precedence_warning is on than when it is off.  Note that we only
need to handle this when testing untransformed child nodes, since the
AEXPR_PAREN nodes will be gone anyway after transformExprRecurse.

Per report from Scott Ribe and additional code-reading.  Back-patch
to 9.5 where this feature was added.

Report: <ED37E303-1B0A-4CD8-8E1E-B9C4C2DD9A17@elevated-dev.com>

Given a left join containing a full join in its righthand side, with
the left join's joinclause referencing only one side of the full join
(in a non-strict fashion, so that the full join doesn't get simplified),
the planner could fail with "failed to build any N-way joins" or related
errors.  This happened because the full join was seen as overlapping the
left join's RHS, and then recent changes within join_is_legal() caused
that function to conclude that the full join couldn't validly be formed.
Rather than try to rejigger join_is_legal() yet more to allow this,
I think it's better to fix initsplan.c so that the required join order
is explicit in the SpecialJoinInfo data structure.  The previous coding
there essentially ignored full joins, relying on the fact that we don't
flatten them in the joinlist data structure to preserve their ordering.
That's sufficient to prevent a wrong plan from being formed, but as this
example shows, it's not sufficient to ensure that the right plan will
be formed.  We need to work a bit harder to ensure that the right plan
looks sane according to the SpecialJoinInfos.

Per bug #14105 from Vojtech Rylko.  This was apparently induced by
commit 8703059c (though now that I've seen it, I wonder whether there
are related cases that could have failed before that); so back-patch
to all active branches.  Unfortunately, that patch also went into 9.0,
so this bug is a regression that won't be fixed in that branch.

The coverage was rather lean for cases that bind() or listen() might
return.  Add entries for everything that there's a direct equivalent
for in the set of Unix errnos that elog.c has heard of.

There's no longer a need for the MSVC-version-specific code stanza that
forcibly redefines errno code symbols, because since commit 73838b52 we're
unconditionally redefining them in the stanza before this one anyway.
Now it's merely confusing and ugly, so get rid of it; and improve the
comment that explains what's going on here.

Although this is just cosmetic, back-patch anyway since I'm intending
to back-patch some less-cosmetic changes in this same hunk of code.

Revert commit 7cb1db1d, which represented
a misunderstanding of the problem (if snapmgr.h weren't already included
in bufmgr.h, things wouldn't compile anywhere).  Instead install what
I think is the real fix.

When we shoehorned "x op ANY (array)" into the SQL syntax, we created a
fundamental ambiguity as to the proper treatment of a sub-SELECT on the
righthand side: perhaps what's meant is to compare x against each row of
the sub-SELECT's result, or perhaps the sub-SELECT is meant as a scalar
sub-SELECT that delivers a single array value whose members should be
compared against x.  The grammar resolves it as the former case whenever
the RHS is a select_with_parens, making the latter case hard to reach ---
but you can get at it, with tricks such as attaching a no-op cast to the
sub-SELECT.  Parse analysis would throw away the no-op cast, leaving a
parsetree with an EXPR_SUBLINK SubLink directly under a ScalarArrayOpExpr.
ruleutils.c was not clued in on this fine point, and would naively emit
"x op ANY ((SELECT ...))", which would be parsed as the first alternative,
typically leading to errors like "operator does not exist: text = text[]"
during dump/reload of a view or rule containing such a construct.  To fix,
emit a no-op cast when dumping such a parsetree.  This might well be
exactly what the user wrote to get the construct accepted in the first
place; and even if she got there with some other dodge, it is a valid
representation of the parsetree.

Per report from Karl Czajkowski.  He mentioned only a case involving
RLS policies, but actually the problem is very old, so back-patch to
all supported branches.

Report: <20160421001832.GB7976@moraine.isi.edu>

Also, avoid reading PGPROC's wait_event field twice, once for the wait
event and again for the wait_event_type, because the value might change
in the middle.

Petr Jelinek and Robert Haas

It's not necessarily just scanning a base relation any more.

Amit Langote and Etsuro Fujita

That commit increased all shared memory allocations to the next higher
multiple of PG_CACHE_LINE_SIZE, but it didn't ensure that allocation
started on a cache line boundary.  It also failed to remove a couple
other pieces of now-useless code.

BUFFERALIGN() is perhaps obsolete at this point, and likely should be
removed at some point, too, but that seems like it can be left to a
future cleanup.

Mistakes all pointed out by Andres Freund.  The patch is mine, with
a few extra assertions which I adopted from his version of this fix.

Windows builds on buildfarm are failing because
old_snapshot_threshold is not found in the bloom filter contrib
module.

This fixes a problem which is not new, but with the advent of direct
foreign table modification in 0bf3ae88,
it's somewhat more likely to be annoying than previously.  So,
arrange for a local query cancelation to propagate to the remote side.

Michael Paquier, reviewed by Etsuro Fujita.	 Original report by
Thom Brown.

Even with old_snapshot_threshold = -1 (which disables the "snapshot
too old" feature), performance regressions were seen at moderate to
high concurrency.  For example, a one-socket, four-core system
running 200 connections at saturation could see up to a 2.3%
regression, with larger regressions possible on NUMA machines.
By inlining the early (smaller, faster) tests in the
TestForOldSnapshot() function, the i7 case dropped to a 0.2%
regression, which could easily just be noise, and is clearly an
improvement.  Further testing will show whether more is needed.

If there's a filter condition on either side of a full outer join,
it is neither correct to attach it to the join's ON clause nor to
throw it into the toplevel WHERE clause.  Just don't push down the
join in that case.

To maximize the number of cases where we can still push down full
joins, push inner join conditions into the ON clause at the first
opportunity rather than postponing them to the top-level WHERE
clause.  This produces nicer SQL, anyway.

This bug was introduced in e4106b25.

Ashutosh Bapat, per report from Rajkumar Raghuwanshi.

In commit 2ffa8696 we made pg_ctl recognize an environment variable
PGCTLTIMEOUT to set the default timeout for starting and stopping the
postmaster.  However, pg_regress uses pg_ctl only for the "stop" end of
that; it has bespoke code for starting the postmaster, and that code has
historically had a hard-wired 60-second timeout.  Further buildfarm
experience says it'd be a good idea if that timeout were also controlled
by PGCTLTIMEOUT, so let's make it so.  Like the previous patch, back-patch
to all active branches.

Discussion: <13969.1461191936@sss.pgh.pa.us>

This was an oversight in commit 41ea0c23.

Fabrízio de Royes Mello, per a report from Tushar Ahuja

That won't work.  You'll get bogus null-extended rows.

Mithun Cy

This includes the rest of the documentation that was not included
in 71176854. A larger restructure would still be wanted, but with
this commit the documentation of the new features is complete.

Commit 36a35c55 turned the interface between ginPlaceToPage and
its subroutines in gindatapage.c and ginentrypage.c into a royal mess:
page-update critical sections were started in one place and finished in
another place not even in the same file, and the very same subroutine
might return having started a critical section or not.  Subsequent patches
band-aided over some of the problems with this design by making things
even messier.

One user-visible resulting problem is memory leaks caused by the need for
the subroutines to allocate storage that would survive until ginPlaceToPage
calls XLogInsert (as reported by Julien Rouhaud).  This would not typically
be noticeable during retail index updates.  It could be visible in a GIN
index build, in the form of memory consumption swelling to several times
the commanded maintenance_work_mem.

Another rather nasty problem is that in the internal-page-splitting code
path, we would clear the child page's GIN_INCOMPLETE_SPLIT flag well before
entering the critical section that it's supposed to be cleared in; a
failure in between would leave the index in a corrupt state.  There were
also assorted coding-rule violations with little immediate consequence but
possible long-term hazards, such as beginning an XLogInsert sequence before
entering a critical section, or calling elog(DEBUG) inside a critical
section.

To fix, redefine the API between ginPlaceToPage() and its subroutines
by splitting the subroutines into two parts.  The "beginPlaceToPage"
subroutine does what can be done outside a critical section, including
full computation of the result pages into temporary storage when we're
going to split the target page.  The "execPlaceToPage" subroutine is called
within a critical section established by ginPlaceToPage(), and it handles
the actual page update in the non-split code path.  The critical section,
as well as the XLOG insertion call sequence, are both now always started
and finished in ginPlaceToPage().  Also, make ginPlaceToPage() create and
work in a short-lived memory context to eliminate the leakage problem.
(Since a short-lived memory context had been getting created in the most
common code path in the subroutines, this shouldn't cause any noticeable
performance penalty; we're just moving the overhead up one call level.)

In passing, fix a bunch of comments that had gone unmaintained throughout
all this klugery.

Report: <571276DD.5050303@dalibo.com>

The reverted changes were intended to force a choice of whether any
newly-added BufferGetPage() calls needed to be accompanied by a
test of the snapshot age, to support the "snapshot too old"
feature.  Such an accompanying test is needed in about 7% of the
cases, where the page is being used as part of a scan rather than
positioning for other purposes (such as DML or vacuuming).  The
additional effort required for back-patching, and the doubt whether
the intended benefit would really be there, have indicated it is
best just to rely on developers to do the right thing based on
comments and existing usage, as we do with many other conventions.

This change should have little or no effect on generated executable
code.

Motivated by the back-patching pain of Tom Lane and Robert Haas

Print the actual value of each function result that's expected to be exact,
rather than merely emitting a NULL if it's not right.  Although we print
these with extra_float_digits = 3, we should not trust that the platform
will produce a result visibly different from the expected value if it's off
only in the last place; hence, also include comparisons against the exact
values as before.  This is a bit bulkier and uglier than the previous
printout, but it will provide more information and be easier to interpret
if there's a test failure.

Discussion: <18241.1461073100@sss.pgh.pa.us>

Coverity complained that oldPartitionLock was possibly dereferenced after
having been set to NULL.  That actually can't happen, because we'd only use
it if (oldFlags & BM_TAG_VALID) is true.  But nonetheless Coverity is
justified in complaining, because at line 1275 we actually overwrite
oldFlags, and then still expect its BM_TAG_VALID bit to be a safe guide to
whether to release the oldPartitionLock.  Thus, the code would be incorrect
if someone else had changed the buffer's BM_TAG_VALID flag meanwhile.
That should not happen, since we hold pin on the buffer throughout this
sequence, but it's starting to look like a rather shaky chain of logic.
And there's no need for such assumptions, because we can simply replace
the (oldFlags & BM_TAG_VALID) tests with (oldPartitionLock != NULL),
which has identical results and makes it plain to all comers that we don't
dereference a null pointer.  A small side benefit is that the range of
liveness of oldFlags is greatly reduced, possibly allowing the compiler
to save a register.

This is just cleanup, not an actual bug fix, so there seems no need
for a back-patch.

Per discussion, there doesn't seem to be much value in having
NUM_SPINLOCK_SEMAPHORES set to 1024: under any scenario where you are
running more than a few backends concurrently, you really had better have a
real spinlock implementation if you want tolerable performance.  And 1024
semaphores is a sizable fraction of the system-wide SysV semaphore limit
on many platforms.  Therefore, reduce this setting's default value to 128
to make it less likely to cause out-of-semaphores problems.

Artur Zakirov

From: Michael Paquier <michael.paquier@gmail.com>

In commit 6f0d6a50 I added a duplicate copy of psqlscanslash's identifier
downcasing code, but actually it's not hard to split that out as a callable
subroutine and avoid the duplication.

We've had repeated troubles over the years with failures to initialize
spinlocks correctly; see 6b93fcd1 for a recent example.  Most of the time,
on most platforms, such oversights can escape notice because all-zeroes is
the expected initial content of an slock_t variable.  The only platform
we have where the initialized state of an slock_t isn't zeroes is HPPA,
and that's practically gone in the wild.  To make it easier to catch such
errors without needing one of those, adjust the --disable-spinlocks code
so that zero is not a valid value for an slock_t for it.

In passing, remove a bunch of unnecessary #include's from spin.c;
commit daa7527a removed all the intermodule coupling that
made them necessary.