Up to now, EXPLAIN has contented itself with printing the sort expressions
in a Sort or Merge Append plan node.  This patch improves that by
annotating the sort keys with COLLATE, DESC, USING, and/or NULLS FIRST/LAST
whenever nondefault sort ordering options are used.  The output is now a
reasonably close approximation of an ORDER BY clause equivalent to the
plan's ordering.

Marius Timmer, Lukas Kreft, and Arne Scheffer; reviewed by Mike Blackwell.
Some additional hacking by me.

Currently, a backend will reset it's PGXACT->xmin value when it doesn't
have any registered snapshots left. That covered the common case that a
transaction in read committed mode runs several queries, one after each
other, as there would be no snapshots active between those queries.
However, if you hold cursors across each of the query, we didn't get a
chance to reset xmin.

To make that better, keep all the registered snapshots in a pairing heap,
ordered by xmin so that it's always quick to find the snapshot with the
smallest xmin. That allows us to advance PGXACT->xmin whenever the oldest
snapshot is deregistered, even if there are others still active.

Per discussion originally started by Jeff Davis back in 2009 and more
recently by Robert Haas.

For no significant extra complexity, we can cache knowledge that the
target page is lossy, and save a hash_search per iteration in that
case as well.  This probably makes little difference, since the extra
rechecks that must occur when pages are lossy are way more expensive
than anything we can save here ... but we might as well do it if we're
going to cache anything.

When adding a large number of tuples to a TID bitmap using
tbm_add_tuples() sometimes a lot of time was spent looking up a page's
entry in the bitmap's internal hashtable.

Improve efficiency by caching the last accessed page, while iterating
over the passed in tuples, hoping consecutive tuples will often be on
the same page.  In many cases that's a good bet, and in the rest the
added overhead isn't big.

Discussion: 54479A85.8060309@sigaev.ru

Author: Teodor Sigaev
Reviewed-By: David Rowley

Previous fix mapped "Norwegian (Bokmål)" locale, which contains a non-ASCII
character, to the pure ASCII alias "norwegian-bokmal". However, it turns
out that more recent versions of the CRT library, in particular MSVCR110
(Visual Studio 2012), changed the behaviour of setlocale() so that if
you pass "norwegian-bokmal" to setlocale, it returns "Norwegian_Norway".

That meant trouble, when setlocale(..., NULL) first returned
"Norwegian (Bokmål)_Norway", which we mapped to "norwegian-bokmal_Norway",
but another call to setlocale(..., "norwegian-bokmal_Norway") returned
"Norwegian_Norway". That caused PostgreSQL to think that they are different
locales, and therefore not compatible. That caused initdb to fail at
CREATE DATABASE.

Older CRT versions seem to accept "Norwegian_Norway" too, so change the
mapping to return "Norwegian_Norway" instead of "norwegian-bokmal".

Backpatch to 9.2 like the previous attempt. We haven't made a release that
includes the previous fix yet, so we don't need to worry about changing the
locale of existing clusters from "norwegian-bokmal" to "Norwegian_Norway".
(Doing any mapping like this at all requires changing the locale of
existing databases; the release notes need to include instructions for
that).

Commit 894459e5 revealed this option to
be broken for NLS builds on Darwin, but "make -C contrib/unaccent check"
and the buildfarm client rely on it.  Fix that configuration by
redefining the option to imply LANG=C on Darwin.  In passing, use LANG=C
instead of LANG=en on Windows; since only postmaster startup uses that
value, testers are unlikely to notice the change.  Back-patch to 9.0,
like the predecessor commit.

Up to now, the "child" executor state trees generated for EvalPlanQual
rechecks have simply shared the ResultRelInfo arrays used for the original
execution tree.  However, this leads to dangling-pointer problems, because
ExecInitModifyTable() is all too willing to scribble on some fields of the
ResultRelInfo(s) even when it's being run in one of those child trees.
This trashes those fields from the perspective of the parent tree, because
even if the generated subtree is logically identical to what was in use in
the parent, it's in a memory context that will go away when we're done
with the child state tree.

We do however want to share information in the direction from the parent
down to the children; in particular, fields such as es_instrument *must*
be shared or we'll lose the stats arising from execution of the children.
So the simplest fix is to make a copy of the parent's ResultRelInfo array,
but not copy any fields back at end of child execution.

Per report from Manuel Kniep.  The added isolation test is based on his
example.  In an unpatched memory-clobber-enabled build it will reliably
fail with "ctid is NULL" errors in all branches back to 9.1, as a
consequence of junkfilter->jf_junkAttNo being overwritten with $7f7f.
This test cannot be run as-is before that for lack of WITH syntax; but
I have no doubt that some variant of this problem can arise in older
branches, so apply the code change all the way back.

The flag is supposed to be copied from the record. Same issue with
track_commit_timestamps, but that's master-only.

Report and fix by Petr Jalinek. Backpatch to 9.4, where wal_log_hints was
added.

The folly of the previous arrangement was just demonstrated: there's no
convenient way to add fields to ExplainState without breaking ABI, even
if callers have no need to touch those fields.  Since we might well need
to do that again someday in back branches, let's change things so that
only explain.c has to have sizeof(ExplainState) compiled into it.  This
costs one extra palloc() per EXPLAIN operation, which is surely pretty
negligible.

As of 9.3, ruleutils.c goes to some lengths to ensure that table and column
aliases used in its output are unique.  Of course this takes more time than
was required before, which in itself isn't fatal.  However, EXPLAIN was set
up so that recalculation of the unique aliases was repeated for each
subexpression printed in a plan.  That results in O(N^2) time and memory
consumption for large plan trees, which did not happen in older branches.

Fortunately, the expensive work is the same across a whole plan tree,
so there is no need to repeat it; we can do most of the initialization
just once per query and re-use it for each subexpression.  This buys
back most (not all) of the performance loss since 9.2.

We need an extra ExplainState field to hold the precalculated deparse
context.  That's no problem in HEAD, but in the back branches, expanding
sizeof(ExplainState) seems risky because third-party extensions might
have local variables of that struct type.  So, in 9.4 and 9.3, introduce
an auxiliary struct to keep sizeof(ExplainState) the same.  We should
refactor the APIs to avoid such local variables in future, but that's
material for a separate HEAD-only commit.

Per gripe from Alexey Bashtanov.  Back-patch to 9.3 where the issue
was introduced.

Previously, read() might have returned a length equal to the buffer
length, and then the subsequent store to buf[len] would write a
zero-byte one byte past the end.  This doesn't seem likely to be
a security issue, but there's some chance it could result in
pg_standby misbehaving.

Spotted by Coverity; patch by Michael Paquier, reviewed by me.

The possibly, depending on compiler settings, generated warning was
"warning: `S_UNLOCK' redefined".

The hppa spinlock implementation doesn't follow the rules of s_lock.h
and provides a gcc specific implementation outside of the the part of
the file that's supposed to do that.  It does so to avoid duplication
between the HP compiler and gcc. That unfortunately means that
S_UNLOCK is already defined when the HPPA specific section is reached.

Undefine the generic fallback S_UNLOCK definition inside the HPPA
section. That's far from pretty, but has the big advantage of being
simple. If somebody is interested to fix this in a prettier way...

This presumably got broken in the course of 0709b7ee.

Discussion: 20150114225919.GY5245@awork2.anarazel.de

Per complaint from Tom Lane.

Michael Paquier

Spotted by Coverity.  This isn't likely to matter in practice, but
there's no harm in fixing it.

Michael Paquier

To do so, move InitializeLatchSupport() into the new common process
initialization functions, and add a new global variable MyLatch.

MyLatch is usable as soon InitPostmasterChild() has been called
(i.e. very early during startup). Initially it points to a process
local latch that exists in all processes. InitProcess/InitAuxiliaryProcess
then replaces that local latch with PGPROC->procLatch. During shutdown
the reverse happens.

This is primarily advantageous for two reasons: For one it simplifies
dealing with the shared process latch, especially in signal handlers,
because instead of having to check for MyProc, MyLatch can be used
unconditionally. For another, a later patch that makes FEs/BE
communication use latches, now can rely on the existence of a latch,
even before having gone through InitProcess.

Discussion: 20140927191243.GD5423@alap3.anarazel.de

Previously, configure would add any switches that it chose of its own
accord to the end of the user-specified CFLAGS string.  Since most
compilers process these left-to-right, this meant that configure's choices
would override the user-specified flags in case of conflicts.  We'd rather
that worked the other way around, so adjust the logic to put the user's
string at the end not the beginning.

There does not seem to be a need for a similar behavior change for CPPFLAGS
or LDFLAGS: in those, the earlier switches tend to win (think -I or -L
behavior) so putting the user's string at the front is fine.

Backpatch to 9.4 but not earlier.  I'm not planning to run buildfarm member
guar on older branches, and it seems a bit risky to change this behavior
in long-stable branches.

Autoconf has known about automatically selecting -Ae when needed for
quite some time now, so remove the redundant addition in template/hpux.
Noted while setting up buildfarm member pademelon.

Since commit 626eb021 has introduced the auxiliary process
infrastructure, bootstrap_signals() was never used when forked from
postmaster.

Remove the IsUnderPostmaster specific code, and add a appropriate
assertion.

Move common code, that was duplicated in every postmaster child/every
standalone process, into two functions in miscinit.c.  Not only does
that already result in a fair amount of net code reduction but it also
makes it much easier to remove more duplication in the future. The
prime motivation wasn't code deduplication though, but easier addition
of new common code.

Commit b94ce6e8 reordered postmaster's startup sequence so that the
tempfile directory is only cleaned up after all the necessary state
for pg_ctl is collected.  Unfortunately the chosen location is after
the syslogger has been started; which normally is fine, except for
!WIN32 EXEC_BACKEND builds, which pass information to children via
files in the temp directory.

Move the call to RemovePgTempFiles() to just before the syslogger has
started. That's the first child we fork.

Luckily EXEC_BACKEND is pretty much only used by endusers on windows,
which has a separate method to pass information to children. That
means the real world impact of this bug is very small.

Discussion: 20150113182344.GF12272@alap3.anarazel.de

Backpatch to 9.1, just as the previous commit was.

Also use lower-case for a few more features, to be consistent with the
others and with the SQL spec.

Similar warnings from backend were silenced earlier by commit c8315930,
but there were a few more contrib/hstore.

Michael Paquier

Since their introduction latches have required barriers in SetLatch
and ResetLatch - but when they were introduced there wasn't any
barrier abstraction. Instead latches were documented to rely on the
callsites to provide barrier semantics.

Now that the barrier support looks halfway complete, add the necessary
barriers to both latch implementations.

Also remove a now superflous lock acquisition from syncrep.c and a
superflous (and insufficient) barrier from freelist.c. There might be
other cases that can now be simplified, but those are the only ones
I've seen on a quick scan.

We might want to backpatch this at some later point, but right now the
barrier infrastructure in the backbranches isn't totally on par with
master.

Discussion: 20150112154026.GB2092@awork2.anarazel.de

So far WaitLatchOrSocket() required to pass in WL_SOCKET_READABLE as
that solely was used to indicate error conditions, like EOF. Waiting
for WL_SOCKET_WRITEABLE would have meant to busy wait upon socket
errors.

Adjust the API to signal errors by returning the socket as readable,
writable or both, depending on WL_SOCKET_READABLE/WL_SOCKET_WRITEABLE
being specified.  It would arguably be nicer to return WL_SOCKET_ERROR
but that's not possible on platforms and would probably also result in
more complex callsites.

This previously had explicitly been forbidden in e42a21b9, as
there was no strong use case at that point. We now are looking into
making FE/BE communication use latches, so changing this makes sense.

There also are some portability concerns because there cases of older
platforms where select(2) is known to, in violation of POSIX, not
return a socket as writable after the peer has closed it.  So far the
platforms where that's the case provide a working poll(2). If we find
one where that's not the case, we'll need to add a workaround for that
platform.

Discussion: 20140927191243.GD5423@alap3.anarazel.de
Reviewed-By: Heikki Linnakangas, Noah Misch

Plus some tiny wordsmithing of not-quite-typos.

Per testing with a compiler that whines about this.

I noticed the "vacuum" regression test taking really significantly longer
than it used to on a slow machine.  Investigation pointed the finger at
commit e415b469, which added creation of
an index using an extremely expensive index function.  That function was
evidently meant to be applied only twice ... but the test re-used an
existing test table, which up till a couple lines before that had had over
two thousand rows.  Depending on timing of the concurrent regression tests,
the intervening VACUUMs might have been unable to remove those
recently-dead rows, and then the index build would need to create index
entries for them too, leading to the wrap_do_analyze() function being
executed 2000+ times not twice.  Avoid this by using a different table
that is guaranteed to have only the intended two rows in it.

Back-patch to 9.0, like the commit that created the problem.

Some spaces were missing, and putting the affected tuple offset first in
the lock cases instead of the locking data makes more sense.

No backpatch since this is cosmetic and surrounding code has changed.

Commit 3f88672a neglected to update the AlterExtensionContentsStmt
production in the grammar to use TypeName to represent types when
passing objects to get_object_address.

Reported as a pg_upgrade failure by Jeff Janes.

The mechanism added in commit dbdf9679
for associating the correct translation domain with errcontext strings
potentially fails in cases where errcontext() is used within an ereport()
macro.  Such usage was not originally envisioned for errcontext(), but we
do have a few places that do it.  In this situation, the intended comma
expression becomes just a couple of arguments to errfinish(), which the
compiler might choose to evaluate right-to-left.

Fortunately, in such cases the textdomain for the errcontext string must
be the same as for the surrounding ereport.  So we can fix this by letting
errstart initialize context_domain along with domain; then it will have
the correct value no matter which order the calls occur in.  (Note that
error stack callback functions are not invoked until errfinish, so normal
usage of errcontext won't affect what happens for errcontext calls within
the ereport macro.)

In passing, make sure that errcontext calls within the main backend set
context_domain to something non-NULL.  This isn't a live bug because
NULL would select the current textdomain() setting which should be the
right thing anyway --- but it seems better to handle this completely
consistently with the regular domain field.

Per report from Dmitry Voronin.  Backpatch to 9.3; before that, there
wasn't any attempt to ensure that errcontext strings were translated
in an appropriate domain.

Back in ed0b409d, PGPROC was split and moved to static variables in
procarray.c, with procs in ProcArrayStruct replaced by an array of
integers representing process numbers (pgprocnos), with -1 indicating a
dead process which has yet to be removed.  Access to procArray is
generally done under ProcArrayLock and therefore most code does not have
to concern itself with -1 entries.

However, MinimumActiveBackends intentionally does not take
ProcArrayLock, which means it has to be extra careful when accessing
procArray.  Prior to ed0b409d, this was handled by checking for a NULL
in the pointer array, but that check was no longer valid after the
split.  Coverity pointed out that the check could never happen and so
it was removed in 5592ebac.  That didn't make anything worse, but it
didn't fix the issue either.

The correct fix is to check for pgprocno == -1 and skip over that entry
if it is encountered.

Back-patch to 9.2, since there can be attempts to access the arrays
prior to their start otherwise.  Note that the changes prior to 9.4 will
look a bit different due to the change in 5592ebac.

Note that MinimumActiveBackends only returns a bool for heuristic
purposes and any pre-array accesses are strictly read-only and so there
is no security implication and the lack of fields complaints indicates
it's very unlikely to run into issues due to this.

Pointed out by Noah.

Commit 0eea8047 introduced some overly
optimistic assumptions about what could be in a local struct variable's
initializer.  (This might in fact be valid code according to C99, but I've
got at least one pre-C99 compiler that falls over on those nonconstant
address expressions.)  There is no reason whatsoever for main()'s workspace
to not be static, so revert long_options[] to a static and make the
DumpOptions struct static as well.

We had code that supposed that some platforms might offer a nonstandard
version of getpwuid_r() with only four arguments.  However, the 5-argument
definition has been standardized at least since the Single Unix Spec v2,
which is our normal reference for what's portable across all Unix-oid
platforms.  (What's more, this wasn't the only pre-standardization version
of getpwuid_r(); my old HPUX 10.20 box has still another signature.)
So let's just get rid of the now-useless configure step.

Some users run their applications in chroot environments that lack an
/etc/passwd file.  This means that the current UID's user name and home
directory are not obtainable.  libpq used to be all right with that,
so long as the database role name to use was specified explicitly.
But commit a4c8f143 broke such cases by
causing any failure of pg_fe_getauthname() to be treated as a hard error.
In any case it did little to advance its nominal goal of causing errors
in pg_fe_getauthname() to be reported better.  So revert that and instead
put some real error-reporting code in place.  This requires changes to the
APIs of pg_fe_getauthname() and pqGetpwuid(), since the latter had
departed from the POSIX-specified API of getpwuid_r() in a way that made
it impossible to distinguish actual lookup errors from "no such user".

To allow such failures to be reported, while not failing if the caller
supplies a role name, add a second call of pg_fe_getauthname() in
connectOptions2().  This is a tad ugly, and could perhaps be avoided with
some refactoring of PQsetdbLogin(), but I'll leave that idea for later.
(Note that the complained-of misbehavior only occurs in PQsetdbLogin,
not when using the PQconnect functions, because in the latter we will
never bother to call pg_fe_getauthname() if the user gives a role name.)

In passing also clean up the Windows-side usage of GetUserName(): the
recommended buffer size is 257 bytes, the passed buffer length should
be the buffer size not buffer size less 1, and any error is reported
by GetLastError() not errno.

Per report from Christoph Berg.  Back-patch to 9.4 where the chroot
failure case was introduced.  The generally poor reporting of errors
here is of very long standing, of course, but given the lack of field
complaints about it we won't risk changing these APIs further back
(even though they're theoretically internal to libpq).

If the compiler/arch combination does not provide compiler barriers,
provide a fallback. That fallback simply consists out of a function
call into a externally defined function.  That should guarantee
compiler barrierer semantics except for compilers that do inter
translation unit/global optimization - those better provide an actual
compiler barrier.

Hopefully this fixes Tom's report of linker failures due to
pg_compiler_barrier_impl not being provided.

I'm not backpatching this commit as it builds on the new atomics
infrastructure. If we decide an equivalent fix needs to be
backpatched, I'll do so in a separate commit.

Discussion: 27746.1420930690@sss.pgh.pa.us

Per report from Tom Lane.

I failed to recognize that pg_atomic_uint64 wasn't guaranteed to be 8
byte aligned on some 32bit platforms - which it has to be on some
platforms to guarantee the desired atomicity and which we assert.

As this is all compiler specific code anyway we can just rely on
compiler specific tricks to enforce alignment.

I've been unable to find concrete documentation about the version that
introduce the sunpro alignment support, so that might need additional
guards.

I've verified that this works with gcc x86 32bit, but I don't have
access to any other 32bit environment.

Discussion: op.xpsjdkil0sbe7t@vld-kuci

Per report from Vladimir Koković.

Report by Jeff Davis

Report by Tatsuo Ishii, Coverity

Wee -> We.

Pointed out by Etsuro Fujita.

For some reason I overlooked in GETTEXT_TRIGGERS that the right argument
be read by gettext in 7fcbf6a4.  This
will drop the translation percentages for the backend all the way back
to 9.3 ...

Problem reported by Heikki.