Management of timeouts was getting a little cumbersome; what we
originally had was more than enough back when we were only concerned
about deadlocks and query cancel; however, when we added timeouts for
standby processes, the code got considerably messier.  Since there are
plans to add more complex timeouts, this seems a good time to introduce
a central timeout handling module.

External modules register their timeout handlers during process
initialization, and later enable and disable them as they see fit using
a simple API; timeout.c is in charge of keeping track of which timeouts
are in effect at any time, installing a common SIGALRM signal handler,
and calling setitimer() as appropriate to ensure timely firing of
external handlers.

timeout.c additionally supports pluggable modules to add their own
timeouts, though this capability isn't exercised anywhere yet.

Additionally, as of this commit, walsender processes are aware of
timeouts; we had a preexisting bug there that made those ignore SIGALRM,
thus being subject to unhandled deadlocks, particularly during the
authentication phase.  This has already been fixed in back branches in
commit 0bf8eb2a, which see for more details.

Main author: Zoltán Böszörményi
Some review and cleanup by Álvaro Herrera
Extensive reworking by Tom Lane

The Solaris Studio compiler warns about these instances, unlike more
mainstream compilers such as gcc.  But manual inspection showed that
the code is clearly not reachable, and we hope no worthy compiler will
complain about removing this code.

Formerly, when trying to copy both indexes and comments, CREATE TABLE LIKE
had to pre-assign names to indexes that had comments, because it made up an
explicit CommentStmt command to apply the comment and so it had to know the
name for the index.  This creates bad interactions with other indexes, as
shown in bug #6734 from Daniele Varrazzo: the preassignment logic couldn't
take any other indexes into account so it could choose a conflicting name.

To fix, add a field to IndexStmt that allows it to carry a comment to be
assigned to the new index.  (This isn't a user-exposed feature of CREATE
INDEX, only an internal option.)  Now we don't need preassignment of index
names in any situation.

I also took the opportunity to refactor DefineIndex to accept the IndexStmt
as such, rather than passing all its fields individually in a mile-long
parameter list.

Back-patch to 9.2, but no further, because it seems too dangerous to change
IndexStmt or DefineIndex's API in released branches.  The bug exists back
to 9.0 where CREATE TABLE LIKE grew the ability to copy comments, but given
the lack of prior complaints we'll just let it go unfixed before 9.2.

rfree() failed to cope with the case that pg_regcomp() had initialized the
regex_t struct but then failed to allocate any memory for re->re_guts (ie,
the first malloc call in pg_regcomp() failed).  It would try to touch the
guts struct anyway, and thus dump core.  This is a sufficiently narrow
corner case that it's not surprising it's never been seen in the field;
but still a bug is a bug, so patch all active branches.

Noted while investigating whether we need to call pg_regfree after a
failure return from pg_regcomp.  Other than this bug, it turns out we
don't, so adjust comments appropriately.

This was causing a compiler warning with Solaris compiler. Use 0 instead.
The variable is initialized just for the sake of tidyness  and/or debugging,
it's not used for anything before setting it to a real value.

Per report and suggestion from Peter Eisentraut.

This makes it easier to determine how far back you need to keep archived WAL
files, to restore from a backup.

Fujii Masao

Historically we have not worried about fsync'ing anything during initdb
(in fact, initdb intentionally passes -F to each backend launch to prevent
it from fsync'ing).  But with filesystems getting more aggressive about
caching data, that's not such a good plan anymore.  Make initdb do a pass
over the finished data directory tree to fsync everything.  For testing
purposes, the -N/--nosync flag can be used to restore the old behavior.

Also, testing shows that on Linux, sync_file_range() is much faster than
posix_fadvise() for hinting to the kernel that an fsync is coming,
apparently because the latter blocks on a rather small request queue while
the former doesn't.  So use this function if available in initdb, and also
in the backend's pg_flush_data() (where it currently will affect only the
speed of CREATE DATABASE's cloning step).

We will later make pg_regress invoke initdb with the --nosync flag
to avoid slowing down cases such as "make check" in contrib.  But
let's not do so until we've shaken out any portability issues in this
patch.

Jeff Davis, reviewed by Andres Freund

Make it clearer that the passed stack mustn't be empty, and that we
are not supposed to fall off the end of the stack in the main loop.
Tighten the loop that extracts the root block number, too.

Markus Wanner and Tom Lane

found by P. Broennimann

When reading from a text- or CSV-format file in file_fdw, the datatype
input routines can consume a significant fraction of the runtime.
Often, the query does not need all the columns, so we can get a useful
speed boost by skipping I/O conversion for unnecessary columns.

To support this, add a "convert_selectively" option to the core COPY code.
This is undocumented and not accessible from SQL (for now, anyway).

Etsuro Fujita, reviewed by KaiGai Kohei

Dunstan.

When the internal loop mode was added, freeing memory and closing
filedescriptors before returning became important, and a few cases
in the code missed that.

Fujii Masao

These functions support removing or replacing array element value(s)
matching a given search value.  Although intended mainly to support a
future array-foreign-key feature, they seem useful in their own right.

Marco Nenciarini and Gabriele Bartolini, reviewed by Alex Hunsaker

pg_upgrade.

Backpatch to 9.2.

Per buildfarm complaints.

source code(lisp/international/mule-conf.el).  These charsets have not
been supported up to now anyway, so this is just for adding
commentary.  Also add mention that we follow emacs's implementation,
not xemacs's.

Also some cosmetic improvements for wchar-to-mblen patch.

When in SQL_ASCII encoding, strings passed around are not necessarily
UTF8-safe.  We had already fixed this in some places, but it looks like
we missed some.

I had to backpatch Peter Eisentraut's a8b92b60 to 9.1 in order for this
patch to cherry-pick more cleanly.

Patch from Alex Hunsaker, tweaked by Kyotaro HORIGUCHI and myself.

Some desultory cleanup and comment addition by me, during patch review.

Per bug report from Christoph Berg in
20120209102116.GA14429@msgid.df7cb.de

To generate btree-indexable conditions from regex WHERE conditions (such as
WHERE indexed_col ~ '^foo'), we need to be able to identify any fixed
prefix that a regex might have; that is, find any string that must be a
prefix of all strings satisfying the regex.  We used to do that with
entirely ad-hoc code that looked at the source text of the regex.  It
didn't know very much about regex syntax, which mostly meant that it would
fail to identify some optimizable cases; but Viktor Rosenfeld reported that
it would produce actively wrong answers for quantified parenthesized
subexpressions, such as '^(foo)?bar'.  Rather than trying to extend the
ad-hoc code to cover this, let's get rid of it altogether in favor of
identifying prefixes by examining the compiled form of a regex.

To do this, I've added a new entry point "pg_regprefix" to the regex library;
hopefully it is defined in a sufficiently general fashion that it can remain
in the library when/if that code gets split out as a standalone project.

Since this bug has been there for a very long time, this fix needs to get
back-patched.  However it depends on some other recent commits (particularly
the addition of wchar-to-database-encoding conversion), so I'll commit this
separately and then go to work on back-porting the necessary fixes.

Previously, pattern_fixed_prefix() was defined to return whatever fixed
prefix it could extract from the pattern, plus the "rest" of the pattern.
That definition was sensible for LIKE patterns, but not so much for
regexes, where reconstituting a valid pattern minus the prefix could be
quite tricky (certainly the existing code wasn't doing that correctly).
Since the only thing that callers ever did with the "rest" of the pattern
was to pass it to like_selectivity() or regex_selectivity(), let's cut out
the middle-man and just have pattern_fixed_prefix's subroutines do this
directly.  Then pattern_fixed_prefix can return a simple selectivity
number, and the question of how to cope with partial patterns is removed
from its API specification.

While at it, adjust the API spec so that callers who don't actually care
about the pattern's selectivity (which is a lot of them) can pass NULL for
the selectivity pointer to skip doing the work of computing a selectivity
estimate.

This patch is only an API refactoring that doesn't actually change any
processing, other than allowing a little bit of useless work to be skipped.
However, it's necessary infrastructure for my upcoming fix to regex prefix
extraction, because after that change there won't be any simple way to
identify the "rest" of the regex, not even to the low level of fidelity
needed by regex_selectivity.  We can cope with that if regex_fixed_prefix
and regex_selectivity communicate directly, but not if we have to work
within the old API.  Hence, back-patch to all active branches.

We can do this without creating an API break for estimation functions
by passing the collation using the existing fmgr functionality for
passing an input collation as a hidden parameter.

The need for this was foreseen at the outset, but we didn't get around to
making it happen in 9.1 because of the decision to sort all pg_statistic
histograms according to the database's default collation.  That meant that
selectivity estimators generally need to use the default collation too,
even if they're estimating for an operator that will do something
different.  The reason it's suddenly become more interesting is that
regexp interpretation also uses a collation (for its LC_TYPE not LC_COLLATE
property), and we no longer want to use the wrong collation when examining
regexps during planning.  It's not that the selectivity estimate is likely
to change much from this; rather that we are thinking of caching compiled
regexps during planner estimation, and we won't get the intended benefit
if we cache them with a different collation than the executor will use.

Back-patch to 9.1, both because the regexp change is likely to get
back-patched and because we might as well get this right in all
collation-supporting branches, in case any third-party code wants to
rely on getting the collation.  The patch turns out to be minuscule
now that I've done it ...

The previous coding abused the first element of a cNFA state's arcs list
to hold a per-state flag bit, which was confusing, undocumented, and not
even particularly efficient.  Get rid of that in favor of a separate
"stflags" vector.  Since there's only one bit in use, I chose to allocate a
char per state; we could possibly replace this with a bitmap at some point,
but that would make accesses a little slower.  It's already about 8X
smaller than before, so let's not get overly tense.

Also document the representation better than it was before, which is to say
not at all.

This patch is a byproduct of investigations towards extracting a "fixed
prefix" string from the compact-NFA representation of regex patterns.
Might need to back-patch it if we decide to back-patch that fix, but for
now it's just code cleanup so I'll just put it in HEAD.

This should ease its use on the Windows build environment.

Commit 2b443063 changed wording for some of the error messages, but
neglected updating the regress output to match.

\copyright output to 2012.

Backpatch to 9.2.

to avoid producing dups, e.g. 2012-2012

Backpatch to 9.2.

match, so files that contain embedded copyrights are updated, e.g.
pgsql/help.c.

Backpatch to 9.2.

basename() qualification.

(now added).

Backpatch to 9.2.

Bug spotted by Tom Lane.

report from Tom.

Backpatch to 9.2.

join_path_components() tried to remove leading ".." components from its
tail argument, but it was not nearly bright enough to do so correctly
unless the head argument was (a) absolute and (b) canonicalized.
Rather than try to fix that logic, let's just get rid of it: there is no
correctness reason to remove "..", and cosmetic concerns can be taken
care of by a subsequent canonicalize_path() call.  Per bug #6715 from
Greg Davidson.

Back-patch to all supported branches.  It appears that pre-9.2, this
function is only used with absolute paths as head arguments, which is why
we'd not noticed the breakage before.  However, third-party code might be
expecting this function to work in more general cases, so it seems wise
to back-patch.

In HEAD and 9.2, also make some minor cosmetic improvements to callers.

That caused the plpython_unicode regression test to fail on SQL_ASCII
encoding, as evidenced by the buildfarm. The reason is that with the patch,
you don't get the detail in the error message that you got before. That
detail is actually very informative, so rather than just adjust the expected
output, let's revert that part of the patch for now to make the buildfarm
green again, and figure out some other way to avoid the recursion of
PLy_elog() that doesn't lose the detail.

Windows encodings, "win1252" and so forth, are named differently in Python,
like "cp1252". Also, if the PyUnicode_AsEncodedString() function call fails
for some reason, use a plain ereport(), not a PLy_elog(), to report that
error. That avoids recursion and crash, if PLy_elog() tries to call
PLyUnicode_Bytes() again.

This fixes bug reported by Asif Naeem. Backpatch down to 9.0, before that
plpython didn't even try these conversions.

Jan Urbański, with minor comment improvements by me.

All Unix-oid platforms that we currently support should have waitpid(),
since it's in V2 of the Single Unix Spec.  Our git history shows that
the wait3 code was added to support NextStep, which we officially dropped
support for as of 9.2.  So get rid of the configure test, and simplify the
macro spaghetti in reaper().  Per suggestion from Fujii Masao.

Currently only pg_clog is copied, but some other directories could need
the same treatment as well, so create a subroutine to do it.

Extracted from my (somewhat larger) FOR KEY SHARE patch.