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== Wöchentlicher PostgreSQL Newsletter - 17. April 2011 ==

From: Andreas 'ads' Scherbaum <adsmail(at)wars-nicht(dot)de>
To: "pgsql-de-allgemein(at)postgresql(dot)org" <pgsql-de-allgemein(at)postgresql(dot)org>
Cc: "pgusers(at)postgres(dot)de" <pgusers(at)postgres(dot)de>
Subject: == Wöchentlicher PostgreSQL Newsletter - 17. April 2011 ==
Date: 2011-04-21 18:48:41
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Lists: pgsql-de-allgemein

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== Wöchentlicher PostgreSQL Newsletter - 17. April 2011 ==

PostgreSQL Updates 9.04, 8.4.8, 8.3.15, und 8.2.21 erscheinen bald.
Fertigmachen zum Upgrade!

== PostgreSQL Produkt Neuigkeiten ==

tail_n_mail 1.18.1, ein Programm zum Überwachen von
Logdateien, ist erschienen.

Bucardo 4.4.3, ein Postgres Multi-Master Replikationssystem,
ist erschienen.

== PostgreSQL Jobs im April ==

== PostgreSQL Lokal ==

Die Türkische PostgreSQL User Group organisiert eine eintägige
Veranstaltung am 30. April 2011. Folge @PgDayTR für Details,
auf Türkisch.

Das Open Database Camp findet vom 7. bis 9. Mai 2011 in Sardinien,
Italien statt.

PGCon findet am 19. und 20. Mai 2011 an der Universität
von Ottawa statt, vorher gibt es am 17. und 18. Mai
zwei Tage mit Trainings.

PG Session 2 über PostGIS findet am 23. Juni in Paris statt.
Der Call for Papers ist jetzt offen.

pgbr findet in Sao Paulo, Brazilien, am 3. und 4. November 2011 statt.

== PostgreSQL in den News ==

Planet PostgreSQL:

Dieser wöchentliche PostgreSQL Newsletter wurde erstellt von David Fetter.

Sende Neuigkeiten und Ankündigungen bis Sonntag, 15 Uhr Pazifischer
Zeit. Bitte sende englische Beiträge an david(at)fetter(dot)org, deutsche an
pwn(at)pgug(dot)de, italienische an pwn(at)itpug(dot)org, spanische an pwn(at)arpug(dot)com(dot)ar(dot)

== Reviews ==

== Angewandte Patches ==

Heikki Linnakangas pushed:

- TransferPredicateLocksToNewTarget should initialize a new lock
   entry's commitSeqNo to that of the old one being transferred, or
   take the minimum commitSeqNo if it is merging two lock entries.
   Also, CreatePredicateLock should initialize commitSeqNo for to
   InvalidSerCommitSeqNo instead of to 0. (I don't think using 0 would
   actually affect anything, but we should be consistent.) I also added
   a couple of assertions I used to track this down: a lock's
   commitSeqNo should never be zero, and it should be
   InvalidSerCommitSeqNo if and only if the lock is not held by
   OldCommittedSxact.  Dan Ports, to fix leak of predicate locks
   reported by YAMAMOTO Takashi.

- Fix the size of predicate lock manager's shared memory hash tables
   at creation.  This way they don't compete with the regular lock
   manager for the slack shared memory, making the behavior more

- On IA64 architecture, we check the depth of the register stack in
   addition to the regular stack. The code to do that is platform and
   compiler specific, add support for the HP-UX native compiler.

- Revert the patch to check if we've reached end-of-backup also when
   doing crash recovery, and throw an error if not. hubert depesz
   lubaczewski pointed out that that situation also happens in the
   crash recovery following a system crash that happens during an
   online backup.  We might want to do something smarter in 9.1, like
   put the check back for backups taken with pg_basebackup, but that's
   for another patch.

- On HP/UX, the structs used by ioctl(SIOCGLIFCONF) are named
   differently than on other platforms, and only IPv6 addresses are
   returned.  Because of those two issues, fall back to
   ioctl(SIOCGIFCONF) on HP/UX, so that it at least compiles and finds
   IPv4 addresses. This function is currently only used for
   interpreting samehost/samenet in pg_hba.conf, which isn't that

- Reduce the initial size of local lock hash to 16 entries.  The hash
   table is seq scanned at transaction end, to release all locks, and
   making the hash table larger than necessary makes that slower.  With
   very simple queries, that overhead can amount to a few percent of
   the total CPU time used.  At the moment, backend startup needs 6
   locks, and a simple query with one table and index needs 3 locks. 16
   is enough for even quite complicated transactions, and it will grow
   automatically if it fills up.

- setlocale() on Windows doesn't work correctly if the locale name
   contains apostrophes or dots. There isn't much hope of Microsoft
   fixing it any time soon, it's been like that for ages, so we better
   work around it. So, map a few common Windows locale names known to
   cause problems to aliases that work.

- On Windows, if the encoding implied by locale is not allowed as a
   server-encoding, fall back to UTF-8. It happens at least with the
   Chinese locale, which implies BIG5. This is safe, because on Windows
   all locales are compatible with UTF-8.

Tom Lane pushed:

- Teach pattern_fixed_prefix() about collations.  This is necessary,
   not optional, now that ILIKE and regexes are collation aware ---
   else we might derive a wrong comparison constant for index optimized
   pattern matches.

- Fix RI_Initial_Check to use a COLLATE clause when needed in its
   query.  If the referencing and referenced columns have different
   collations, the parser will be unable to resolve which collation to
   use unless it's helped out in this way.  The effects are sometimes
   masked, if we end up using a non-collation-sensitive plan; but if we
   do use a mergejoin we'll see a failure, as recently noted by Robert
   Haas.  The SQL spec states that the referenced column's collation
   should be used to resolve RI checks, so that's what we do.  Note
   however that we currently don't append a COLLATE clause when writing
   a query that examines only the referencing column.  If we ever
   support collations that have varying notions of equality, that will
   have to be changed.  For the moment, though, it's preferable to
   leave it off so that we can use a normal index on the referencing

- Be more wary of missing statistics in eqjoinsel_semi().  In
   particular, if we don't have real ndistinct estimates for both
   sides, fall back to assuming that half of the left-hand rows have
   join partners.  This is what was done in 8.2 and 8.3 (cf
   nulltestsel() in those versions).  It's pretty stupid but it won't
   lead us to think that an antijoin produces no rows out, as seen in
   recent example from Uwe Schroeder.

- Suppress compiler warnings about "value computed is not used".  The
   recent patch to remove gcc 4.6 warnings created some new ones, at
   least on my rather old gcc version.  Try to make everybody happy by
   casting to "void" when we just want to discard the result.

- Pass collations to functions in FunctionCallInfoData, not FmgrInfo.
   Since collation is effectively an argument, not a property of the
   function, FmgrInfo is really the wrong place for it; and this
   becomes critical in cases where a cached FmgrInfo is used for
   varying purposes that might need different collation settings.  Fix
   by passing it in FunctionCallInfoData instead.  In particular this
   allows a clean fix for bug #5970 (record_cmp not working).  This
   requires touching a bit more code than the original method, but
   nobody ever thought that collations would not be an invasive

- Fix broken pg_dump query.  The 8.4 branch failed when talking to 7.0
   servers.  Per testing requested by Bruce.

- Add some useful cross-references to the CREATE EXTENSION reference
   page.  Per a suggestion from Josh Kupershmidt, though I modified his
   patch quite a lot.

- Update time zone data files to tzdata release 2011f.  DST law
   changes in Chile, Cuba, Falkland Islands, Morocco, Samoa, Turkey.
   Historical corrections for South Australia, Alaska, Hawaii.

- Ensure mark_dummy_rel doesn't create dangling pointers in
   RelOptInfos.  When we are doing GEQO join planning, the current
   memory context is a short-lived context that will be reset at the
   end of geqo_eval().  However, the RelOptInfos for base relations are
   set up before that and then re-used across many GEQO cycles.  Hence,
   any code that modifies a baserel during join planning has to be
   careful not to put pointers to the short-lived context into the
   baserel struct.  mark_dummy_rel got this wrong, leading to
   easy-to-reproduce-once-you-know-how crashes in 8.4, as reported
   off-list by Leo Carson of SDSC.  Some improvements made in 9.0 make
   it difficult to demonstrate the crash in 9.0 or HEAD; but there's no
   doubt that there's still a risk factor here, so patch all branches
   that have the function.  (Note: 8.3 has a similar function, but it's
   only applied to joinrels and thus is not a hazard.)

- Update release notes for releases 9.0.4, 8.4.8, 8.3.15, and 8.2.21.

- Guard against incoming rowcount estimate of NaN in cost_mergejoin().
   Although rowcount estimates really ought not be NaN, a bug elsewhere
   could perhaps result in that, and that would cause Assert failure in
   cost_mergejoin, which I believe to be the explanation for bug #5977
   from Anton Kuznetsov.  Seems like a good idea to expend a couple
   more cycles to prevent that, even though the real bug is elsewhere.
   Not back-patching, though, because we don't encourage running
   production systems with Asserts on.

- Suppress unused-function warning on non-WIN32 builds.

- Prevent incorrect updates of pg_index while reindexing pg_index
   itself.  The places that attempt to change pg_index.indcheckxmin
   during a reindexing operation cannot be executed safely if pg_index
   itself is the subject of the operation.  This is the explanation for
   a couple of recent reports of VACUUM FULL failing with
     ERROR: duplicate key value violates unique constraint 
     DETAIL:  Key (indexrelid)=(2678) already exists.
   However, there isn't any real need to update indcheckxmin in such a
   situation, if we assume that pg_index can never contain a truly
   broken HOT chain.  This assumption holds if new indexes are never
   created on it during concurrent operations, which is something we
   don't consider safe for any system catalog, not just pg_index.
   Accordingly, modify the code to not manipulate indcheckxmin when
   reindexing any system catalog.  Back-patch to 8.3, where HOT was
   introduced.  The known failure scenarios involve 9.0-style VACUUM
   FULL, so there might not be any real risk before 9.0, but let's not
   assume that.

- Clean up collation processing in prepunion.c.  This area was a few
   bricks shy of a load, and badly under-commented too.  We have to
   ensure that the generated targetlist entries for a set-operation
   node expose the correct collation for each entry, since higher-level
   processing expects the tlist to reflect the true ordering of the
   plan's output.  This hackery wouldn't be necessary if
   SortGroupClause carried collation info ... but making it do so would
   inject more pain in the parser than would be saved here.  Still, we
   might want to rethink that sometime.

- Simplify reindex_relation's API.  For what seem entirely historical
   reasons, a bitmask "flags" argument was recently added to
   reindex_relation without subsuming its existing boolean argument
   into that bitmask.  This seems a bit bizarre, so fold them together.

- Add an Assert that indexam.c isn't used on an index awaiting
   reindexing.  This might have caught the recent embarrassment over
   trying to modify pg_index while its indexes were being rebuilt.
   Noah Misch

- foreach() and list_delete() don't mix.  Fix crash when releasing
   duplicate entries in the encoding conversion cache list, caused by
   releasing the current entry of the list being chased by foreach().
   We have a standard idiom for handling such cases, but this loop
   wasn't using it.  This got broken in my recent rewrite of GUC assign
   hooks.  Not sure how I missed this when testing the modified code,
   but I did.  Per report from Peter.

- Support a COLLATE clause in plpgsql variable declarations.  This
   allows the usual rules for assigning a collation to a local variable
   to be overridden.  Per discussion, it seems appropriate to support
   this rather than forcing all local variables to have the
   argument-derived collation.

- Add check for matching column collations in ALTER TABLE ... INHERIT.
   The other DDL operations that create an inheritance relationship
   were checking for collation match already, but this one got missed.
   Also fix comments that failed to mention collation checks.

- Fix pg_dump to handle collations applied to columns of composite
   types.  CREATE TYPE and ALTER TYPE ADD ATTRIBUTE handle this, so I
   suppose it's an intended feature, but pg_dump didn't know about it.

- Document COLLATE option in CREATE TYPE reference page.  Curiously,
   it was already documented in ALTER TYPE ADD ATTRIBUTE, but not here.

- Fix assorted infelicities in collation handling in psql's
   describe.c.  In \d, be more careful to print collation only if it's
   not the default for the column's data type.  Avoid assuming that the
   name "default" is magic.  Fix \d on a composite type so that it will
   print per-column collations.  It's no longer the case that a
   composite type cannot have modifiers.  (In consequence, the expected
   outputs for composite-type regression tests change.) Fix \dD so that
   it will print collation for a domain, again only if it's not the
   same as the base type's collation.

Peter Eisentraut pushed:

- Clean up most -Wunused-but-set-variable warnings from gcc 4.6.  This
   warning is new in gcc 4.6 and part of -Wall.  This patch cleans up
   most of the noise, but there are some still warnings that are
   trickier to remove.

- Translation updates.

- Rename pg_regress option --multibyte to --encoding.  Also refactor
   things a little bit so that the same methods for setting test locale
   and encoding can be used everywhere.

- Set client encoding explicitly in plpython_unicode test.  This will
   (hopefully) eliminate the need for the plpython_unicode_0.out
   expected file.

Andrew Dunstan pushed:

- Don't make "replication" magical as a user name, only as a database
   name, in pg_hba.conf.  Per gripe from Josh Berkus. Backported from
   commit ed557a373c406bbb2a1843544ebbd856ca4cac47.

Bruce Momjian pushed:

- Fix pg_upgrade crash.  Fix pg_upgrade crash in 9.0 caused by a new
   cluster database that doesn't exist in the old cluster;  instead
   throw an error.  This was reported to me by EnterpriseDB testing
   staff.  This bug does not exist in git head.

Robert Haas pushed:

- Avoid incorrectly granting replication to roles created with
   NOSUPERUSER.  Andres Freund

- Fix toast table creation.  Instead of using slightly-too-clever
   heuristics to decide when we must create a TOAST table, just check
   whether one is needed every time the table is altered.  Checking
   whether a toast table is needed is cheap enough that we needn't
   worry about doing it on every ALTER TABLE command, and the previous
   coding is apparently prone to accidental breakage: commit
   04e17bae50a73af524731fa11210d5c3f7d8e1f9 broken ALTER TABLE ..  SET
   STORAGE, which moved some actions from AT_PASS_COL_ATTRS to
   AT_PASS_MISC, and commit 6c5723998594dffa5d47c3cf8c96ccf89c033aae
   broke ALTER TABLE .. ADD COLUMN by changing the way that adding
   columns recurses into child tables.  Noah Misch, with one comment
   change by me

- Remove obsolete comment.  The lock level for adding a parent table
   is now ShareUpdateExclusiveLock; see commit
   fbcf4b92aa64d4577bcf25925b055316b978744a.  This comment didn't get
   updated to match, but it doesn't seem important to mention this
   detail here, so rather than updating it now, just take it out.

- Advise Debian/Ubuntu users to use openjade1.3.  The latest openjade
   packages for Ubuntu 10.10 seg fault when building our documentation.
   Josh Berkus

Marc Fournier pushed:

- Tag 9.0.4, 8.4.8, 8.3.15, and 8.2.21.

Magnus Hagander pushed:

- Note that Bison on GnuWin32 has trouble with paths with spaces.
   Peter Eisentraut

- Specify which versions of the Platform SDK are supported.  Anything
   including Visual Studio 2010 compilers is not yet supported for
   building on Windows.

== Abgelehnte Patches (bis jetzt) ==

No one was disappointed this week :-)

== Eingesandte Patches ==

Roman Zotov sent in another revision of the patch to turn PREFERRED
for type from a boolean to an int2, which allows for an expression of

Robert Haas sent in a patch to fix a bug in recoveryStopsHere().

Greg Smith sent in a patch to remove some of the magic from running

Andrew Dunstan sent in two revisions of a patch to remove pgindent
magic in different ways from Greg Smith's.

			Andreas 'ads' Scherbaum
Deutsche PostgreSQL User Group:

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