Don't leak a file descriptor if the file is empty or we can't read its size.

Expect there to be a newline at the end of the last line, too. If there
isn't, ignore anything after the last newline. This makes it a tiny bit
more robust in case the file is appended to concurrently, so that we don't
return the last line if it hasn't been fully written yet. And this makes
the code a bit less obscure, anyway. Per Tom Lane's suggestion.

Backpatch to all supported branches.

for recent concurrent changes.

Abhijit Menon-Sen

Concurrent behaviour was flawed when using
a two-step process, so add an additional
phase of processing to ensure concurrency
for both SELECTs and INSERT/UPDATE/DELETEs.

Backpatch to 9.2

Andres Freund, tweaked by me

If a potential equivalence clause references a variable from the nullable
side of an outer join, the planner needs to take care that derived clauses
are not pushed to below the outer join; else they may use the wrong value
for the variable.  (The problem arises only with non-strict clauses, since
if an upper clause can be proven strict then the outer join will get
simplified to a plain join.)  The planner attempted to prevent this type
of error by checking that potential equivalence clauses aren't
outerjoin-delayed as a whole, but actually we have to check each side
separately, since the two sides of the clause will get moved around
separately if it's treated as an equivalence.  Bugs of this type can be
demonstrated as far back as 7.4, even though releases before 8.3 had only
a very ad-hoc notion of equivalence clauses.

In addition, we neglected to account for the possibility that such clauses
might have nonempty nullable_relids even when not outerjoin-delayed; so the
equivalence-class machinery lacked logic to compute correct nullable_relids
values for clauses it constructs.  This oversight was harmless before 9.2
because we were only using RestrictInfo.nullable_relids for OR clauses;
but as of 9.2 it could result in pushing constructed equivalence clauses
to incorrect places.  (This accounts for bug #7604 from Bill MacArthur.)

Fix the first problem by adding a new test check_equivalence_delay() in
distribute_qual_to_rels, and fix the second one by adding code in
equivclass.c and called functions to set correct nullable_relids for
generated clauses.  Although I believe the second part of this is not
currently necessary before 9.2, I chose to back-patch it anyway, partly to
keep the logic similar across branches and partly because it seems possible
we might find other reasons why we need valid values of nullable_relids in
the older branches.

Add regression tests illustrating these problems.  In 9.0 and up, also
add test cases checking that we can push constants through outer joins,
since we've broken that optimization before and I nearly broke it again
with an overly simplistic patch for this problem.

Implementation idea from Tom Lane

Author: Joel Jacobson
Reviewed by Joachim Wieland

Backpatch to 9.2 to ensure bugs are fixed.

Abhijit Menon-Sen

If an SMgrRelation is not "owned" by a relcache entry, don't allow it to
live past transaction end.  This design allows the same SMgrRelation to be
used for blind writes of multiple blocks during a transaction, but ensures
that we don't hold onto such an SMgrRelation indefinitely.  Because an
SMgrRelation typically corresponds to open file descriptors at the fd.c
level, leaving it open when there's no corresponding relcache entry can
mean that we prevent the kernel from reclaiming deleted disk space.
(While CacheInvalidateSmgr messages usually fix that, there are cases
where they're not issued, such as DROP DATABASE.  We might want to add
some more sinval messaging for that, but I'd be inclined to keep this
type of logic anyway, since allowing VFDs to accumulate indefinitely
for blind-written relations doesn't seem like a good idea.)

This code replaces a previous attempt towards the same goal that proved
to be unreliable.  Back-patch to 9.1 where the previous patch was added.

This reverts commit fba105b1.
That approach had problems with the smgr-level state not tracking what
we really want to happen, and with the VFD-level state not tracking the
smgr-level state very well either.  In consequence, it was still possible
to hold kernel file descriptors open for long-gone tables (as in recent
report from Tore Halset), and yet there were also cases of FDs being closed
undesirably soon.  A replacement implementation will follow.

Provide a common implementation of embedded singly-linked and
doubly-linked lists.  "Embedded" in the sense that the nodes'
next/previous pointers exist within some larger struct; this design
choice reduces memory allocation overhead.

Most of the implementation uses inlineable functions (where supported),
for performance.

Some existing uses of both types of lists have been converted to the new
code, for demonstration purposes.  Other uses can (and probably will) be
converted in the future.  Since dllist.c is unused after this conversion,
it has been removed.

Author: Andres Freund
Some tweaks by me
Reviewed by Tom Lane, Peter Geoghegan

output mode, cause the hex digits after the period to always be at least
four hex digits, with zero-padding.

... because the latter plays games with the privileges for language SQL.
It looks like running alter_generic in parallel with "misc" is OK though.

Also, adjust serial_schedule to maintain the same test ordering (up to
parallelism) as parallel_schedule.

Fujii Masao

AddToDataDirLockFile() supports out-of-order updates of the lockfile
nowadays.

If postmaster changed postmaster.pid while pg_ctl was reading it, pg_ctl
could overrun the buffer it allocated for the file. Fix by reading the
whole file to memory with one read() call.

initdb contains an identical copy of the readfile() function, but the files
that initdb reads are static, not modified concurrently. Nevertheless, add
a simple bounds-check there, if only to silence static analysis tools.

Per report from Dave Vitek. Backpatch to all supported branches.

In the previous coding, new backend processes would attempt to create their
self-pipe during the OwnLatch call in InitProcess.  However, pipe creation
could fail if the kernel is short of resources; and the system does not
recover gracefully from a FATAL error right there, since we have armed the
dead-man switch for this process and not yet set up the on_shmem_exit
callback that would disarm it.  The postmaster then forces an unnecessary
database-wide crash and restart, as reported by Sean Chittenden.

There are various ways we could rearrange the code to fix this, but the
simplest and sanest seems to be to split out creation of the self-pipe into
a new function InitializeLatchSupport, which must be called from a place
where failure is allowed.  For most processes that gets called in
InitProcess or InitAuxiliaryProcess, but processes that don't call either
but still use latches need their own calls.

Back-patch to 9.1, which has only a part of the latch logic that 9.2 and
HEAD have, but nonetheless includes this bug.

In commit 11e13185, I missed the case of
a CTE RTE that doesn't have a user-defined alias, but does have an
alias assigned by set_rtable_names().  Per report from Peter Eisentraut.

While at it, refactor slightly to reduce code duplication.

rather than just storing a pointer.

We don't need this hack any more.

Per compiler warning.

This change ensures that the planner will see implicit and explicit casts
as equivalent for all purposes, except in the minority of cases where
there's actually a semantic difference (as reflected by having a 3-argument
cast function).  In particular, this fixes cases where the EquivalenceClass
machinery failed to consider two references to a varchar column as
equivalent if one was implicitly cast to text but the other was explicitly
cast to text, as seen in bug #7598 from Vaclav Juza.  We have had similar
bugs before in other parts of the planner, so I think it's time to fix this
problem at the core instead of continuing to band-aid around it.

Remove set_coercionform_dontcare(), which represents the band-aid
previously in use for allowing matching of index and constraint expressions
with inconsistent cast labeling.  (We can probably get rid of
COERCE_DONTCARE altogether, but I don't think removing that enum value in
back branches would be wise; it's possible there's third party code
referring to it.)

Back-patch to 9.2.  We could go back further, and might want to once this
has been tested more; but for the moment I won't risk destabilizing plan
choices in long-since-stable branches.

Based on a suggestion by Peter Eisentraut.

When hashing a subplan like "WHERE (a, b) NOT IN (SELECT x, y FROM ...)",
findPartialMatch() attempted to match rows using the hashtable's internal
equality operators, which of course are for x and y's datatypes.  What we
need to use are the potentially cross-type operators for a=x, b=y, etc.
Failure to do that leads to wrong answers or even crashes.  The scope for
problems is limited to cases where we have different types with compatible
hash functions (else we'd not be using a hashed subplan), but for example
int4 vs int8 can cause the problem.

Per bug #7597 from Bo Jensen.  This has been wrong since the hashed-subplan
code was written, so patch all the way back.

Rename replication_timeout to wal_sender_timeout, and add a new setting
called wal_receiver_timeout that does the same at the walreceiver side.
There was previously no timeout in walreceiver, so if the network went down,
for example, the walreceiver could take a long time to notice that the
connection was lost. Now with the two settings, both sides of a replication
connection will detect a broken connection similarly.

It is no longer necessary to manually set wal_receiver_status_interval to
a value smaller than the timeout. Both wal sender and receiver now
automatically send a "ping" message if more than 1/2 of the configured
timeout has elapsed, and it hasn't received any messages from the other end.

Amit Kapila, heavily edited by me.

Numerous flex and bison make rules have appeared in the source tree
over time, and they are all virtually identical, so we can replace
them by pattern rules with some variables for customization.

Users of pgxs will also be able to benefit from this.

Apparently, on some glibc versions this causes warnings when
optimization is not enabled.

Altogether, there appear to be too many incompatibilities surrounding
this.

The HINTs generated for these error cases vary across builds.  We
could try to work around that, but the test cases aren't really useful
enough to justify taking any trouble.

Per buildfarm.

We no longer use GetNewOidWithIndex on pg_largeobject; rather,
pg_largeobject_metadata's regular OID column is considered the repository
of OIDs for large objects.  The special functionality is still needed for
TOAST tables however.

dblink now has its own validator function dblink_fdw_validator(), which is
better than the core function postgresql_fdw_validator() because it gets
the list of legal options from libpq instead of having a hard-wired list.

Make the dblink extension module provide a standard foreign data wrapper
dblink_fdw that encapsulates use of this validator, and recommend use of
that wrapper instead of making up wrappers on the fly.

Unfortunately, because ad-hoc wrappers *were* recommended practice
previously, it's not clear when we can get rid of postgresql_fdw_validator
without causing upgrade problems.  But this is a step in the right
direction.

Shigeru Hanada, reviewed by KaiGai Kohei

Etsuro Fujita, with some wording adjustment by me.

Backpatch to 9.2.

The idea here is to make sure the planner will evaluate these functions
last not first among the filter conditions in psql pattern search and
tab-completion queries.  We've discussed this several times, and there
was consensus to do it back in August, but we didn't want to do it just
before a release.  Now seems like a safer time.

No catversion bump, since this catalog change doesn't create a backend
incompatibility nor any regression test result changes.

Building a shlib on AIX requires use of the mkldexport.sh script, but we
failed to install that, preventing its use from non-source-tree contexts.
Also, Makefile.aix had the wrong idea about where to find the installed
copy of the postgres.imp symbol file used by AIX.

Per report from John Pierce.  Patch all the way back, since this has been
broken since the beginning of PGXS.

Do read/write permissions checks at most once per large object descriptor,
not once per lo_read or lo_write call as before.  The repeated tests were
quite useless in the read case since the snapshot-based tests were
guaranteed to produce the same answer every time.  In the write case,
the extra tests could in principle detect revocation of write privileges
after a series of writes has started --- but there's a race condition there
anyway, since we'd check privileges before performing and certainly before
committing the write.  So there's no real advantage to checking every
single time, and we might as well redefine it as "only check the first
time".

On the same reasoning, remove the LargeObjectExists checks in inv_write
and inv_truncate.  We already checked existence when the descriptor was
opened, and checking again doesn't provide any real increment of safety
that would justify the cost.

I extracted the refactoring patch from a larger patch that contained other
changes too, but missed one unintentional change and didn't test enough...

This is just refactoring with no user-visible effect, to make the code more
readable.