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From: David Fetter <david <at> fetter.org>
Subject: == PostgreSQL Weekly News - November 03 2013 ==
Newsgroups: gmane.comp.db.postgresql.announce
Date: Monday 4th November 2013 04:17:01 UTC (over 3 years ago)
== PostgreSQL Weekly News - November 03 2013 ==

== PostgreSQL Product News ==

direct_cp, a drop-in replacement for cp for use in WAL archiving which
streamlines by using direct IO, released.

grunt-pg-utils implements some things useful during code developement
such as tasks to version control the PostgreSql stored procedures,
automatized database restore/dump and execute query.

ODB 2.3.0, an ORM for C++ which supports PostgreSQL, released.

pgBadger 4.0, a parallel PostgreSQL log analyzer written in Perl,

pg_statsinfo 2.5.0 and pg_stats_reporter 2.0.0 released.

== PostgreSQL Jobs for November ==


== PostgreSQL Local ==

PGConf.DE 2013 will be held November 8th, 2013, at the Rhineland
Industrial Museum in Oberhausen.

The fourth edition of the Argentinian PostgreSQL Day will be held on
November 14 2013 in Buenos Aires, Argentina.

The next meeting of the Indian PostgreSQL User Group will be in Pune
on November 16, 2013.  Info and RSVP:

PGDay Cuba will be November 28-29, 2013.

== PostgreSQL in the News ==

Planet PostgreSQL: http://planet.postgresql.org/

PostgreSQL Weekly News is brought to you this week by David Fetter

Submit news and announcements by Sunday at 3:00pm Pacific time.
Please send English language ones to [email protected], German language
to [email protected], Italian language to [email protected]  Spanish language
to [email protected]

== Applied Patches ==

Tom Lane pushed:

- Suppress duplicate-index-entry warning introduced by previous
  commit.  We don't need two index entries for lo_create pointing at
  the same section.  It's a bit pedantic for the toolchain to warn
  about this, but warn it does.

- Improve documentation about usage of FDW validator functions.  SGML
  documentation, as well as code comments, failed to note that an
  FDW's validator will be applied to foreign-table options for foreign
  tables using the FDW.  Etsuro Fujita

- Prevent using strncpy with src == dest in TupleDescInitEntry.  The C
  and POSIX standards state that strncpy's behavior is undefined when
  source and destination areas overlap.  While it remains dubious
  whether any implementations really misbehave when the pointers are
  exactly equal, some platforms are now starting to force the issue by
  complaining when an undefined call occurs.  (In particular OS X 10.9
  has been seen to dump core here, though the exact set of
  circumstances needed to trigger that remain elusive.  Similar
  behavior can be expected to be optional on Linux and other platforms
  in the near future.)  So tweak the code to explicitly do nothing
  when nothing need be done.  Back-patch to all active branches.  In
  HEAD, this also lets us get rid of an exception in valgrind.supp.
  Per discussion of a report from Matthias Schmitt.

- Fix old typo in comment.  NFAs have children, but their individual
  states don't.

- Fix some odd behaviors when using a SQL-style simple GMT offset
  timezone.  Formerly, when using a SQL-spec timezone setting with a
  fixed GMT offset (called a "brute force" timezone in the code), the
  session_timezone variable was not updated to match the nominal
  timezone; rather, all code was expected to ignore session_timezone
  if HasCTZSet was true.  This is of course obviously fragile, though
  a search of the code finds only timeofday() failing to honor the
  rule.  A bigger problem was that DetermineTimeZoneOffset() supposed
  that if its pg_tz parameter was pointer-equal to session_timezone,
  then HasCTZSet should override the parameter.  This would cause
  datetime input containing an explicit zone name to be treated as
  referencing the brute-force zone instead, if the zone name happened
  to match the session timezone that had prevailed before installing
  the brute-force zone setting (as reported in bug #8572).  The same
  malady could affect AT TIME ZONE operators.  To fix, set up
  session_timezone so that it matches the brute-force zone
  specification, which we can do using the POSIX timezone definition
  syntax "offset", and get rid of the bogus lookaside check in
  DetermineTimeZoneOffset().  Aside from fixing the erroneous behavior
  in datetime parsing and AT TIME ZONE, this will cause the
  timeofday() function to print its result in the user-requested time
  zone rather than some previously-set zone.  It might also affect
  results in third-party extensions, if there are any that make use of
  session_timezone without considering HasCTZSet, but in all cases the
  new behavior should be saner than before.  Back-patch to all
  supported branches.

- Remove internal uses of CTimeZone/HasCTZSet.  The only remaining
  places where we actually look at CTimeZone/HasCTZSet are
  abstime2tm() and timestamp2tm().  Now that session_timezone is
  always valid, we can remove these special cases.  The caller-visible
  impact of this is that these functions now always return a valid
  zone abbreviation if requested, whereas before they'd return a NULL
  pointer if a brute-force timezone was in use.  In the existing code,
  the only place I can find that changes behavior is to_char(), whose
  TZ format code will now print something useful rather than nothing
  for such zones.  (In the places where the returned zone abbreviation
  is passed to EncodeDateTime, the lack of visible change is because
  we've chosen the abbreviation used for these zones to match what
  EncodeTimezone would have printed.) It's likely that there is now a
  fair amount of removable dead code around the call sites, namely
  anything that's meant to cope with getting a NULL timezone
  abbreviation, but I've not made an effort to root that out.  This
  could be back-patched if we decide we'd like to fix to_char()'s
  behavior in the back branches, but there doesn't seem to be much
  enthusiasm for that at present.

- Remove CTimeZone/HasCTZSet, root and branch.  These variables no
  longer have any useful purpose, since there's no reason to
  special-case brute force timezones now that we have a valid
  session_timezone setting for them.  Remove the variables, and remove
  the SET/SHOW TIME ZONE code that deals with them.  The user-visible
  impact of this is that SHOW TIME ZONE will now show a POSIX-style
  zone specification, in the form "<+-offset>-+offset", rather than an
  interval value when a brute-force zone has been set.  While perhaps
  less intuitive, this is a better definition than before because it's
  actually possible to give that string back to SET TIME ZONE and get
  the same behavior, unlike what used to happen.  We did not
  previously mention the angle-bracket syntax when describing POSIX
  timezone specifications; add some documentation so that people can
  figure out what these strings do.  (There's still quite a lot of
  undocumented functionality there, but anybody who really cares can
  go read the POSIX spec to find out about it.  In practice most
  people seem to prefer Olsen-style city names anyway.)

- Ensure all files created for a single BufFile have the same resource
  owner.  Callers expect that they only have to set the right resource
  owner when creating a BufFile, not during subsequent operations on
  it.  While we could insist this be fixed at the caller level, it
  seems more sensible for the BufFile to take care of it.  Without
  this, some temp files belonging to a BufFile can go away too soon,
  eg at the end of a subtransaction, leading to errors or crashes.
  Reported and fixed by Andres Freund.  Back-patch to all active

- Retry after buffer locking failure during SPGiST index creation.
  The original coding thought this case was impossible, but it can
  happen if the bgwriter or checkpointer processes decide to write out
  an index page while creation is still proceeding, leading to a bogus
  "unexpected spgdoinsert() failure" error.  Problem reported by
  Jonathan S. Katz.  Teodor Sigaev

- Prevent memory leaks from accumulating across printtup() calls.
  Historically, printtup() has assumed that it could prevent memory
  leakage by pfree'ing the string result of each output function and
  manually managing detoasting of toasted values.  This amounts to
  assuming that datatype output functions never leak any memory
  internally; an assumption we've already decided to be bogus
  elsewhere, for example in COPY OUT.  range_out in particular is
  known to leak multiple kilobytes per call, as noted in bug #8573
  from Godfried Vanluffelen.  While we could go in and fix that leak,
  it wouldn't be very notationally convenient, and in any case there
  have been and undoubtedly will again be other leaks in other output
  functions.  So what seems like the best solution is to run the
  output functions in a temporary memory context that can be reset
  after each row, as we're doing in COPY OUT.  Some quick
  experimentation suggests this is actually a tad faster than the
  retail pfree's anyway.  This patch fixes all the variants of
  printtup, except for debugtup() which is used in standalone mode.
  It doesn't seem worth worrying about query-lifespan leaks in
  standalone mode, and fixing that case would be a bit tedious since
  debugtup() doesn't currently have any startup or shutdown functions.
  While at it, remove manual detoast management from several other
  output-function call sites that had copied it from printtup().  This
  doesn't make a lot of difference right now, but in view of recent
  discussions about supporting "non-flattened" Datums, we're going to
  want that code gone eventually anyway.  Back-patch to 9.2 where
  range_out was introduced.  We might eventually decide to back-patch
  this further, but in the absence of known major leaks in older
  output functions, I'll refrain for now.

- Get rid of more cases of the "must detoast before output function"
  meme.  I missed that json.c was doing this too, because for some
  bizarre reason it wasn't doing it adjacent to the output function

Andrew Dunstan pushed:

- Work around NetBSD shell issue in pg_upgrade test script.  The
  NetBSD shell apparently returns non-zero from an unset command if
  the variable is already unset. This matters when, as in pg_upgrade's
  test.sh, we are working under 'set -e'. To protect against this, we
  first set the PG variables to an empty string before unsetting them
  completely.  Error found on buildfarm member coypu, solution from
  RĂ©mi Zara.

Robert Haas pushed:

- Modify dynamic shared memory code to use Size rather than uint64.
  This is more consistent with what we do elsewhere.

- Avoid too-large shift on 32-bit Windows.  Apparently, shifts greater
  than or equal to the width of the type are undefined, and can
  surprisingly produce a non-zero value.  Amit Kapila, with a comment
  by me.

- Use appendStringInfoString instead of appendStringInfo where
  possible.  This shaves a few cycles, and generally seems like good
  programming practice.  David Rowley

Kevin Grittner pushed:

- Fix subquery reference to non-populated MV in CMV.  A subquery
  reference to a matview should be allowed by CREATE MATERIALIZED VIEW
  WITH NO DATA, just like a direct reference is.  Per bug report from
  Laurent Sartran.  Backpatch to 9.3.

- Acquire appropriate locks when rewriting during RMV.  Since the
  query has not been freshly parsed when executing REFRESH
  MATERIALIZED VIEW, locks must be explicitly taken before rewrite.
  Backpatch to 9.3.  Andres Freund

Michael Meskes pushed:

- Changed test case slightly so it doesn't have an unused typedef.

== Rejected Patches (for now) ==

No one was disappointed this week :-)

== Pending Patches ==

Asif Naeem sent in another revision of a patch to patch a
vulnerability in the Windows version of psql.

Nigel Heron sent in another revision of a patch to add stats for
network traffic.

Amit Kapila sent in a patch to fix an issue where in the Windows
implementation of dynamic shared memory, the Size calculation for
creating dynamic shared memory is assuming that requested size for
creation of dynamic shared memory segment is uint64, which is no
longer the correct type.

Abhijit Menon-Sen sent in a patch to round the size of dynamic shared
memory up a multiple of 2MB unconditionally, and adds a DEBUG1 log
message when the attempt with MAP_HUGETLB fails, falling back to
ordinary mmap.

Gurjeet Singh sent in a patch to shave a few instructions from
child-process startup sequence.

Kyotaro HORIGUCHI sent in a WIP patch to enable using indexes in a
UNION query.

MauMau sent in three revisions of a patch to fix a bug where
PostgreSQL fails to start on Windows if it crashes after tablespace

Robert Haas sent in a set of patches to: 1. add the concept of
on_dsm_detach hooks.  2. provide a facility for sizing a dynamic
shared memory segment before creation, and for dividing it up into
chunks after it's been created.  3. Create an infrastructure for
sending and receiving messages of arbitrary length using ring buffers
stored in shared memory (presumably dynamic shared memory, but
hypothetically the main shared memory segment could be used).  4.
a demonstration of how to use the various background worker and
dynamic shared memory facilities introduced over the course of the 9.4
release cycle, and the facilities introduced by patches #1-#3 of this
series, to actually do something interesting.

Kyotaro HORIGUCHI sent in a patch to get more from indexes in the
UNION [ALL] cases.

Kyotaro HORIGUCHI sent in a patch to add a fallocate() system call to
improve sequential read/write peformance.

Antonin Houska sent in a patch to allow a reference to the parent
query from any sublink.

Etsuro Fujita sent in a patch to show lossy heap block info in the
EXPLAIN ANALYZE output for bitmap heap scans.

Kevin Grittner sent in a patch to silence some compiler warnings.

Mitsumasa KONDO sent in a patch to add an "accurate" option to

Teodor Sigaev sent in a patch to fix a bug in SP-GiST index creation.

Craig Ringer sent in a patch to add writer-side checks to row-based
access control.

Mika Eloranta sent in a patch to fix a bug in pg_receivelog where it
calculated the xlog segment number incorrectly when started after the
previous instance was interrupted.

Andres Freund sent in a patch to fix an issue where it currently is
possible that buffile.c segments get created belonging to the wrong
resource owner leading to WARNINGs ala "temporary file leak: File %d
still referenced", ERRORs like "write failed", asserts and segfaults.

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