This is more efficient and simpler . It does mean that an untyped NULL
can no longer be used in such cases, which should be mentioned in
Release Notes, but doesn't seem a terrible loss. The workaround is to
cast the NULL to some array type.

Pavel Stehule, reviewed by Jeevan Chalke.

Should use RelationGetIndexPredicate(), since rd_indpred is just a cache
that is not computed until/unless demanded.  Per buildfarm failure on
CLOBBER_CACHE_ALWAYS animals; diagnosis and fix by Hitoshi Harada.

On HPPA, implement pg_memory_barrier() as pg_compiler_barrier(), which
should be correct since this arch doesn't do memory access reordering,
and is anyway better than the completely-nonfunctional-on-this-arch
dummy_spinlock code.  (But note this patch only fixes things for gcc,
not for builds with HP's compiler.)

Also, fix incorrect default definition of pg_memory_barrier as a macro
requiring an argument.

Also, fix incorrect spelling of "#elif" as "#else if" in icc code path
(spotted by pgindent).

This doesn't come close to fixing all of the functional and stylistic
deficiencies in barrier.h, but at least it un-breaks my personal build.
Now that we're actually using barriers in the code, this file is going
to need some serious attention.

Also, in another comment, explain why holding an insertion slot is a
critical section.

Per review by Amit Kapila.

Initialization of the first XLOG buffer at end-of-recovery was broken for
the case that the last read WAL record ended at a page boundary. Instead of
trying to copy the last full xlog page to the buffer cache in that case,
just set shared state so that the next page is initialized when the first
WAL record after startup is inserted. (that's what we did in earlier
version, too)

To make the shared state required for that case less surprising, replace the
XLogCtl->curridx variable, which was the index of the latest initialized
buffer, with an XLogRecPtr of how far the buffers have been initialized.
That also allows us to get rid of the XLogRecEndPtrToBufIdx macro.

While we're at it, make a similar change for XLogCtl->Write.curridx, getting
rid of that variable and calculating the next buffer to write from
XLogCtl->LogwrtResult instead.

After the recent pglz optimization patch, the next/prev pointers in the
hash table are never NULL, INVALID_ENTRY_PTR is used to represent invalid
entries instead. The end-of-loop check in pglz_find_match() function didn't
get the memo. The result was the same from a correctness point of view, but
because the NULL-check would never fail, the tiny optimization turned into
a pessimization.

Reported by Stephen Frost, using Coverity scanner.

Since this function assumed non-MVCC snapshots, it broke when commit
568d4138 switched its one caller from
SnapshotNow scans to MVCC-snapshot scans.

Reviewed by Robert Haas, Tom Lane and Andres Freund.

This is SQL-standard with a few extensions, namely support for
subqueries and outer references in clause expressions.

catversion bump due to change in Aggref and WindowFunc.

David Fetter, reviewed by Dean Rasheed.

This allows reads to continue without any blocking while a REFRESH
runs.  The new data appears atomically as part of transaction
commit.

Review questioned the Assert that a matview was not a system
relation.  This will be addressed separately.

Reviewed by Hitoshi Harada, Robert Haas, Andres Freund.
Merged after review with security patch f3ab5d46.

There is a new API, RegisterDynamicBackgroundWorker, which allows
an ordinary user backend to register a new background writer during
normal running.  This means that it's no longer necessary for all
background workers to be registered during processing of
shared_preload_libraries, although the option of registering workers
at that time remains available.

When a background worker exits and will not be restarted, the
slot previously used by that background worker is automatically
released and becomes available for reuse.  Slots used by background
workers that are configured for automatic restart can't (yet) be
released without shutting down the system.

This commit adds a new source file, bgworker.c, and moves some
of the existing control logic for background workers there.
Previously, there was little enough logic that it made sense to
keep everything in postmaster.c, but not any more.

This commit also makes the worker_spi contrib module into an
extension and adds a new function, worker_spi_launch, which can
be used to demonstrate the new facility.

The returned error message already includes a newline, but the callers
were adding their own when printing it out.

When creating a sort to support a group by, we need to look up the
target entry in the target list by the resno using get_tle_by_resno().
This particular code-path didn't check the result prior to attempting
to dereference it, while all other callers did.  While I can't see a
way for this usage of get_tle_by_resno() to fail (you can't ask for
a column to be sorted on which isn't included in the group by), it's
probably best to check that we didn't end up with a NULL somehow
anyway than risk the segfault.

I'm willing to back-patch this if others feel it's necessary, but my
guess is new features are what might tickle this rather than anything
existing.

Missing check spotted by the Coverity scanner.

Josh Kupershmidt

Andres Freund

Robins Tharakan, reviewed by Szymon Guz, substantially revised by me.

In pg_basebackup.c:reached_end_position(), we're reading from an
internal pipe with our own background process but we're possibly
reading more bytes than will actually fit into our buffer due to
an off-by-one error.  As we're reading from an internal pipe
there's no real risk here, but it's good form to not depend on
such convenient arrangements.

Bug spotted by the Coverity scanner.

Back-patch to 9.2 where this showed up.

In pg_dump.c:getEventTriggers, check what major version we are on
before calling createPQExpBuffer() to avoid leaking that bit of
memory.

Leak discovered by the Coverity scanner.

Back-patch to 9.3 where support for dumping event triggers was
added.

When creating the symlink for the xlog directory, free the string
which stores the link location.  Not really an issue but it doesn't
hurt to be good about this- prior cleanups have fixed similar
issues.

Leak found by the Coverity scanner.

Not back-patching as I don't see it being worth the code churn.

In receivelog.c:writeTimeLineHistoryFile(), we were not properly
closing the open'd file descriptor in error cases.  While this
wouldn't matter much if we were about to exit due to such an
error, that's not the case with pg_receivexlog as it can be a
long-running process and these errors are non-fatal.

This resource leak was found by the Coverity scanner.

Back-patch to 9.3 where this issue first appeared.

In tuplesort.c:inittapes(), we calculate tapeSpace by first figuring
out how many 'tapes' we can use (maxTapes) and then multiplying the
result by the tape buffer overhead for each.  Unfortunately, when
we are on a system with an 8-byte long, we allow work_mem to be
larger than 2GB and that allows maxTapes to be large enough that the
32bit arithmetic can overflow when multiplied against the buffer
overhead.

When this overflow happens, we end up adding the overflow to the
amount of space available, causing the amount of memory allocated to
be larger than work_mem.

Note that to reach this point, you have to set work mem to at least
24GB and be sorting a set which is at least that size.  Given that a
user who can set work_mem to 24GB could also set it even higher, if
they were looking to run the system out of memory, this isn't
considered a security issue.

This overflow risk was found by the Coverity scanner.

Back-patch to all supported branches, as this issue has existed
since before 8.4.

In streamutil.c:GetConnection(), upgrade failure to parse the
connection string to an exit(1) instead of simply returning NULL.
Most callers already immediately exited, but pg_receivexlog would
loop on this case, continually trying to re-parse the connection
string (which can't be changed after pg_receivexlog has started).

GetConnection() was already expected to exit(1) in some cases
(eg: failure to allocate memory or if unable to determine the
integer_datetimes flag), so this change shouldn't surprise anyone.

Began looking at this due to the Coverity scanner complaining that
we were leaking err_msg in this case- no longer an issue since we
just exit(1) immediately.

The command strings read by the child processes during parallel
pg_dump, after being read and handled, were not being free'd.
This patch corrects this relatively minor memory leak.

Leak found by the Coverity scanner.

Back patch to 9.3 where parallel pg_dump was introduced.

This is like shared_preload_libraries except that it takes effect at
backend start and can be changed without a full postmaster restart.  It
is like local_preload_libraries except that it is still only settable by
a superuser.  This can be a better way to load modules such as
auto_explain.

Since there are now three preload parameters, regroup the documentation
a bit.  Put all parameters into one section, explain common
functionality only once, update the descriptions to reflect current and
future realities.
Reviewed-by: NDimitri Fontaine <dimitri@2ndQuadrant.fr>

This makes superuser-issued REFRESH MATERIALIZED VIEW safe regardless of
the object's provenance.  REINDEX is an earlier example of this pattern.
As a downside, functions called from materialized views must tolerate
running in a security-restricted operation.  CREATE MATERIALIZED VIEW
need not change user ID.  Nonetheless, avoid creation of materialized
views that will invariably fail REFRESH by making it, too, start a
security-restricted operation.

Back-patch to 9.3 so materialized views have this from the beginning.

Reviewed by Kevin Grittner.

Itanium doesn't have the mfence instruction - that's a 386 thing. Use the
"mf" instruction instead.

This reverts the previous commit to add "#include <emmintrinsic.h>"; the
problem was not with a missing #include.

Hopefully this fixes the build failure on buildfarm member dugong.

path_encode's "closed" argument used to take three values: TRUE, FALSE,
or -1, while being of type bool.  Replace that with a three-valued enum
for more clarity.

Was broken by my xloginsert scaling patch. XLogCtl global variable needs
to be initialized in each process, as it's not inherited by fork() on
Windows.

This patch replaces WALInsertLock with a number of WAL insertion slots,
allowing multiple backends to insert WAL records to the WAL buffers
concurrently. This is particularly useful for parallel loading large amounts
of data on a system with many CPUs.

This has one user-visible change: switching to a new WAL segment with
pg_switch_xlog() now fills the remaining unused portion of the segment with
zeros. This potentially adds some overhead, but it has been a very common
practice by DBA's to clear the "tail" of the segment with an external
pg_clearxlogtail utility anyway, to make the WAL files compress better.
With this patch, it's no longer necessary to do that.

This patch adds a new GUC, xloginsert_slots, to tune the number of WAL
insertion slots. Performance testing suggests that the default, 8, works
pretty well for all kinds of worklods, but I left the GUC in place to allow
others with different hardware to test that easily. We might want to remove
that before release.

Reviewed by Andres Freund.

The code in set_append_rel_pathlist() for building parameterized paths
for append relations (inheritance and UNION ALL combinations) supposed
that the cheapest regular path for a child relation would still be cheapest
when reparameterized.  Which might not be the case, particularly if the
added join conditions are expensive to compute, as in a recent example from
Jeff Janes.  Fix it to compare child path costs *after* reparameterizing.
We can short-circuit that if the cheapest pre-existing path is already
parameterized correctly, which seems likely to be true often enough to be
worth checking for.

Back-patch to 9.2 where parameterized paths were introduced.

Use "MXID" as placeholder for -m option, instead of just "XID".

Looks like a cut/paste error in the original addition of the file.

Andres Freund

Avoid output formatting differences by printing str() instead of repr()
of the value.

On some platforms, posix_fallocate() is available but may still return
EINVAL if the underlying filesystem does not support it.  So, in case
of an error, fall through to the alternate implementation that just
writes zeros.

Per buildfarm failure and analysis by Tom Lane.