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Wöchentlicher PostgreSQL Newsletter - 29. April 2007


Der Originalartikel befindet sich unter:
http://people.planetpostgresql.org/dfetter/

== Wöchentlicher PostgreSQL Newsletter - 29. April 2007 ==

Bugfix Versionen 8.2.4, 8.1.9, 8.0.13, 7.4.17 and 7.3.19 sind erschienen.
Upgrade bitte jetzt planen :)

== PostgreSQL Produkt Neuigkeiten ==

EnterpriseDB 8.2 erschienen.
http://www.enterprisedb.com/news_events/press_releases/04_23_07.do

Ein Volltext Wörterbuch für Italienisch ist unter GPL veröffentlicht worden.
http://www.develer.com/~piro/ispell-italian/italian-fts.html

Continuent Uni/Cluster für PostgreSQL 2007 erschienen.
http://www.continuent.com/index.php?option=com_content&task=view&id=212&Itemid=169

== PostgreSQL Jobs im April ==


http://archives.postgresql.org/pgsql-jobs/2007-04/threads.php

== PostgreSQL Lokal ==


Auf gehts zum PgDay!
http://www.pgday.it/en/node/95

Registrierung für PGCon 2007 ist eröffnet
http://www.pgcon.org/2007/registration.php

== PostgreSQL in den News ==

Planet PostgreSQL: http://www.planetpostgresql.org/

General Bits, Archive und gelegentliche News Artikel:
http://www.varlena.com/GeneralBits/

Dieser wöchentliche PostgreSQL Newsletter wurde erstellt von David Fetter.

Um deine Beiträge für die nächste Ausgabe zu übermitteln, sende diese an david@fetter.org oder in Deutsch an pwn@pgug.de bis Sonntag, 15:00 Uhr Pazifischer Zeit.
== Angewandte Patches ==

Michael Meskes committed:

- Removed non-existant function from extern.h

- Inlined two functions to get rid of va_list problems on some archs.

Tom Lane committed:

- Implement rate-limiting logic on how often backends will attempt to
send messages to the stats collector. This avoids the problem that
enabling stats_row_level for autovacuum has a significant overhead
for short read-only transactions, as noted by Arjen van der Meijden.
We can avoid an extra gettimeofday call by piggybacking on the one
done for WAL-logging xact commit or abort (although that doesn't
help read-only transactions, since they don't WAL-log anything). In
my proposal for this, I noted that we could change the WAL log
entries for commit/abort to record full TimestampTz precision,
instead of only time_t as at present. That's not done in this
patch, but will be committed separately.

- Marginal performance hack: use a dedicated routine instead of
copyObject to copy nodes that are known to be Vars during plan
reference adjustment. Saves useless memzero operation as well as
the big switch in copyObject.

- Marginal performance hack: avoid unnecessary work in
expression_tree_mutator. We can just palloc, instead of using
makeNode, when we are going to overwrite the whole node anyway in
the FLATCOPY macro. Also, use FLATCOPY instead of copyObject for
common node types Var and Const.

- Marginal performance hack: remove the loop that used to be needed to
look through a freelist for a chunk of adequate size. For a long
time now, all elements of a given freelist have been exactly the
same allocated size, so we don't need a loop. Since the loop never
iterated more than once, you'd think this wouldn't matter much, but
it makes a noticeable savings in a simple test --- perhaps because
the compiler isn't optimizing on a mistaken assumption that the loop
would repeat. AllocSetAlloc is called often enough that saving even
a couple of instructions is worthwhile.

- Modify processing of DECLARE CURSOR and EXPLAIN so that they can
resolve the types of unspecified parameters when submitted via
extended query protocol. This worked in 8.2 but I had broken it
during plancache changes. DECLARE CURSOR is now treated almost
exactly like a plain SELECT through parse analysis, rewrite, and
planning; only just before sending to the executor do we divert it
away to ProcessUtility. This requires a special-case check in a
number of places, but practically all of them were already
special-casing SELECT INTO, so it's not too ugly. (Maybe it would
be a good idea to merge the two by treating IntoClause as a form of
utility statement? Not going to worry about that now, though.)
That approach doesn't work for EXPLAIN, however, so for that I
punted and used a klugy solution of running parse analysis an extra
time if under extended query protocol.

- Fix dynahash.c to suppress hash bucket splits while a
hash_seq_search() scan is in progress on the same hashtable. This
seems the least invasive way to fix the recently-recognized problem
that a split could cause the scan to visit entries twice or (with
much lower probability) miss them entirely. The only field-reported
problem caused by this is the "failed to re-find shared lock object"
PANIC in COMMIT PREPARED reported by Michel Dorochevsky, which was
caused by multiply visited entries. However, it seems certain that
mdsync() is vulnerable to missing required fsync's due to missed
entries, and I am fearful that RelationCacheInitializePhase2() might
be at risk as well. Because of that and the generalized hazard
presented by this bug, back-patch all the supported branches. Along
the way, fix pg_prepared_statement() and pg_cursor() to not assume
that the hashtables they are examining will stay static between
calls. This is risky regardless of the newly noted dynahash
problem, because hash_seq_search() has never promised to cope with
deletion of table entries other than the just-returned one. There
may be no bug here because the only supported way to call these
functions is via ExecMakeTableFunctionResult() which will cycle them
to completion before doing anything very interesting, but it seems
best to get rid of the assumption. This affects 8.2 and HEAD only,
since those functions weren't there earlier.

- Support explicit placement of the temporary-table schema within
search_path. This is needed to allow a security-definer function to
set a truly secure value of search_path. Without it, a malicious
user can use temporary objects to execute code with the privileges
of the security-definer function. Even pushing the temp schema to
the back of the search path is not quite good enough, because a
function or operator at the back of the path might still capture
control from one nearer the front due to having a more exact
datatype match. Hence, disable searching the temp schema altogether
for functions and operators. Security: CVE-2007-2138

Bruce Momjian committed:

- Update TODO, change version number, "Make
standard_conforming_strings the default in 8.4?"

- In TODO, mark "PL/PgSQL MOVE" as done.

- Remove tabs from installation.sgml.

- Jun Kuwamura's update to the Japanese FAQs.

- Fix typo in FAQ.

- Update FAQ item on upgrades.

Magnus Hagander committed:

- In pgsql/src/tools/msvc/Mkvcbuild.pm, properly set MODULE_PATHNAME
based on module name instead of incorrectly based on directory name.
Fixes the generation of .sql files in contrib/spi. Per complaint
from Dave Page.

- In pgsql/src/tools/msvc/Mkvcbuild.pm, libpgtypes is a client lib,
should not link with backend.

- In pgsql/src/tools/msvc/Solution.pm, generate "fake configure
output" for pg_config, so that external builds like Slony can figure
out which options were enabled in the build.

- Dave Page's patch to install libpgport.lib as needed by some client
programs.

- Dave Page's patch to install headers in the same directory structure
as Mingw.

- In pgsql/src/backend/port/win32_sema.c, set maximum semaphore count
to 32767 instead of 1. Fixes errorcode 298 when unlocking a
semaphore more than once. Back-patched to 8.2. Per report from
Marcin Waldowski.

- In pgsql/src/tools/msvc/Install.pm, don't try to install uuid-ossp
since we don't build it. Per buildfarm member mastodon.

Neil Conway committed:

- Support for MOVE in PL/PgSQL. Initial patch from Magnus, some
improvements by Pavel Stehule, and reviewed by Neil Conway.

- Add support for IN as alternative to FROM in PL/PgSQL's FETCH
statement, for consistency with the backend's FETCH command. Patch
from Pavel Stehule, reviewed by Neil Conway.

- Remove no-longer-true statement from the docs. Since the default
config now enables row-level stats, the out of the box stats volume
is no longer particularly low.

- Another tweak for tab completion of CREATE TEMP. Instead of only
completing CREATE { TEMP | TEMPORARY } TABLE, we should also suggest
VIEW and SEQUENCE. Per Greg Sabino Mullane.

- Consistency tweaks for a table in the SGML docs: we don't terminate
table entries describing functions with periods.

- Minor enhancement to psql tab completion. If we see "CREATE
TEMPORARY", we can complete "TABLE". The previous coding only looked
for "CREATE TEMP". Note that I didn't add TEMPORARY to the list of
suggested completions after we've seen "CREATE", since TEMP is
equivalent and more concise. But if the user has already manually
typed TEMPORARY, we may as well complete TABLE for them.

- Minor tweak for DISCARD ref page.

- Rename the newly-added commands for discarding session state. RESET
SESSION, RESET PLANS, and RESET TEMP are now DISCARD ALL, DISCARD
PLANS, and DISCARD TEMP, respectively. This is to avoid confusion
with the pre-existing RESET variants: the DISCARD commands are not
actually similar to RESET. Patch from Marko Kreen, with some minor
editorialization.

- Minor consistency tweak for SGML docs.

- Fix newly-introduced documentation typo in
pgsql/doc/src/sgml/ref/create_function.sgml

- Heikki Linnakangas's patch which fixes LOCK_DEBUG compilation in the
8.2 branch; HEAD was fixed earlier.

== Abgelehnte Patches (bis jetzt) ==

No one was disappointed this week :-)

== Eingesandte Patches ==

Theo Schlossnagle sent in a patch to correct PL/Perl's handling of
bytea input types.

ITAGAKI Takahiro sent in version 4.1 of his Load Distributed
Checkpoint patch.

ITAGAKI Takahiro sent in a patch to fix autovacuum startup.

Gregory Stark sent in another revision of his SORT/LIMIT optimization.

Neil Conway sent in a patch to allow hashing NUMERICs.

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