Extend cube on-disk format to pack points more tightly.

If the lower left and upper right corners of a cube are the same, set a
flag in the cube header, and only store one copy of the coordinates. That
cuts the on-disk size into half for the common case that the cube datatype
is used to represent points rather than boxes.

The new format is backwards-compatible with the old one, so pg_upgrade
still works. However, to get the space savings, the data needs to be
rewritten. A simple VACUUM FULL or REINDEX is not enough, as the old
Datums will just be moved to the new heap/index as is. A pg_dump and
reload, or something similar like casting to text and back, will do the
trick.

This patch deliberately doesn't update all the alternative expected output
files, as I don't have access to machines that produce those outputs. I'm
not sure if they are still relevant, but if they are, the buildfarm will
tell us and produce the diff required to fix it. If none of the buildfarm
animals need them, they should be removed altogether.

Patch by Stas Kelvich.
Fix blatantly broken record_image_cmp() logic for pass-by-value fields.

Doesn't anybody here pay attention to compiler warnings?
Adjust cube.out expected output for new test queries.

Previous commit modified the test case, but I didn't update cube.out
expected output file in previous commit because it was not needed by the
platforms I have easy access to. Buildfarm animal 'dugong', running
"Debian 4.0 icc 10.1.011 ia64", has now gone red because of that, so update
it now.

Also adjust cube_3.out. According to git history, it was added to support
64-bit MinGW. There is no such animal in the buildfarm, so I'm doing this
blindly, but it was added quite recently so maybe someone still cares.
Make use of psprintf() in recent changes
Get rid of use of asprintf() in favor of a more portable implementation.

asprintf(), aside from not being particularly portable, has a fundamentally
badly-designed API; the psprintf() function that was added in passing in
the previous patch has a much better API choice.  Moreover, the NetBSD
implementation that was borrowed for the previous patch doesn't work with
non-C99-compliant vsnprintf, which is something we still have to cope with
on some platforms; and it depends on va_copy which isn't all that portable
either.  Get rid of that code in favor of an implementation similar to what
we've used for many years in stringinfo.c.  Also, move it into libpgcommon
since it's not really libpgport material.

I think this patch will be enough to turn the buildfarm green again, but
there's still cosmetic work left to do, namely get rid of pg_asprintf()
in favor of using psprintf().  That will come in a followon patch.
Replace pg_asprintf() with psprintf().

This eliminates an awkward coding pattern that's also unnecessarily
inconsistent with backend coding.  psprintf() is now the thing to
use everywhere.
Suppress a couple of compiler warnings seen with older gcc versions.

To wit,
bgworker.c: In function `RegisterDynamicBackgroundWorker':
bgworker.c:761: warning: `generation' might be used uninitialized in this function
dsm_impl.c: In function `dsm_impl_op':
dsm_impl.c:197: warning: control reaches end of non-void function

Neither of these represent actual bugs, but we may as well tweak the code
so that more compilers can tell that.  This won't change the generated code
on compilers that do recognize that the cases are unreachable.
Fix two bugs in setting the vm bit of empty pages.

Use a critical section when setting the all-visible flag on an empty page,
and WAL-logging it. log_newpage_buffer() contains an assertion that it
must be called inside a critical section, and it's the right thing to do
when modifying a buffer anyway.

Also, the page should be marked dirty before calling log_newpage_buffer(),
per the comment in log_newpage_buffer() and src/backend/access/transam/README.

Patch by Andres Freund, in response to my report. Backpatch to 9.2, like
the patch that introduced these bugs (a6370fd9).
Simplify tab completion rules for views and foreign tables.

Since an increasing number of views and foreign tables are now able
to be updated, complete with any table, view, or foreign table in
the relevant contexts.  This avoids the need to use a complex
query that may be both confusing to end-users and nonperformant
to construct the list of possible completions.

Dean Rasheed, persuant to a complaint from Bernd Helme and a
suggestion from Peter Eisentraut
Fix typos in comments.
Fix memory leak when an empty ident file is reloaded.

Hari Babu
Plug memory leak when reloading config file.

The absolute path to config file was not pfreed. There are probably more
small leaks here and there in the config file reload code and assign hooks,
and in practice no-one reloads the config files frequently enough for it to
be a problem, but this one is trivial enough that might as well fix it.

Backpatch to 9.3 where the leak was introduced.
Improve documentation of random() function.

Move random() and setseed() to a separate table, to have them grouped
together. Also add a notice that random() is not cryptographically secure.

Original patch by Honza Horak, although I didn't use his version.
Increase the number of different values used when seeding random().

When a backend process is forked, we initialize the system's random number
generator with srandom(). The seed used is derived from the backend's pid
and the timestamp. However, we only used the microseconds part of the
timestamp, and it was XORed with the pid, so the total range of different
seed values chosen was 0-999999. That's quite limited.

Change the code to also use the seconds part of the timestamp in the seed,
and shift the microseconds so that all 32 bits of the seed are used.

Honza Horak
Use improved vsnprintf calling logic in more places.

When we are using a C99-compliant vsnprintf implementation (which should be
most places, these days) it is worth the trouble to make use of its report
of how large the buffer needs to be to succeed.  This patch adjusts
stringinfo.c and some miscellaneous usages in pg_dump to do that, relying
on the logic recently added in libpgcommon's psprintf.c.  Since these
places want to know the number of bytes written once we succeed, modify the
API of pvsnprintf() to report that.

There remains near-duplicate logic in pqexpbuffer.c, but since that code
is in libpq, psprintf.c's approach of exit()-on-error isn't appropriate
for use there.  Also note that I didn't bother touching the multitude
of places that call (v)snprintf without any attempt to provide a resizable
buffer.

Release-note-worthy incompatibility: the API of appendStringInfoVA()
changed.  If there's any third-party code that's calling that directly,
it will need tweaking along the same lines as in this patch.

David Rowley and Tom Lane
Ignore SIGSYS during initdb.

This prevents the recently-added probe for shm_open() from crashing
on platforms that are impolite enough to deliver a signal rather than
returning ENOSYS for an unimplemented kernel call.  At least on the
one known example (HPUX 10.20), ignoring SIGSYS does result in the
desired behavior of getting an ENOSYS error return instead.

Per discussion, we might later wish to do this in the backend as well,
but for now it seems sufficient to do it in initdb.
Tweak "line" test to avoid negative zeros on some platforms
Revert "Tweak "line" test to avoid negative zeros on some platforms"

This reverts commit a0a546f0d94ec6cbb3cd6b1c82f58d801046615f.
It seems better to tweak the code to suppress -0 results during
line_construct_pts(), which I'll do in the next commit.
Suppress -0 in the C field of lines computed by line_construct_pts().

It's not entirely clear why some PPC machines are generating -0 here, since
the underlying computation should be exactly 0 - 0.  Perhaps there's some
wider-than-nominal-precision calculations happening?  Anyway, the best way
to avoid platform-dependent results seems to be to explicitly reset -0 to
regular zero.
Improve pqexpbuffer.c to use modern vsnprintf implementations efficiently.

When using a C99-compliant vsnprintf, we can use its report of the required
buffer size to avoid making multiple loops through the formatting logic.
This is similar to the changes recently made in stringinfo.c, but we can't
use psprintf.c here because in libpq we don't want to exit() on error.
(The behavior pqexpbuffer.c has historically used is to mark the
PQExpBuffer as "broken", ie empty, if it runs into any fatal problem.)

To avoid duplicating code more than necessary, I refactored
printfPQExpBuffer and appendPQExpBuffer to share a subroutine that's
very similar to psprintf.c's pvsnprintf in spirit.