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Wöchentlicher PostgreSQL Newsletter - 06. Mai 2007


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

== Wöchentlicher PostgreSQL Newsletter - 06. Mai 2007 ==

Das erste road2pgday Gespräch fand diese Woche statt. Die italienische Seite hat Unterlagen.
http://www.pghost.eu/node/9
Hier ist das Video.
http://www.youtube.com/profile?user=neothezion

== PostgreSQL Produkt Neuigkeiten ==


DataArchitect 4.0 erschienen.
http://www.thekompany.com/products/dataarchitect/

psqlODBC 08.02.0400 erschienen.
http://psqlodbc.projects.postgresql.org/release.html

pyswarm 0.7.1 erschienen.
http://pyswarm.sourceforge.net/

== PostgreSQL Jobs im Mai ==

http://archives.postgresql.org/pgsql-jobs/2007-05/threads.php

== PostgreSQL Lokal ==

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

Auf gehts zum PgDay!
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 ==

Bruce Momjian committed:

- Update TODO to reflect new direction in plan tracking and
invalidation.

- Mark TODO as done: "Allow multiple vacuums so large tables do not
starve small."

- Wording update to FAQ_DEV..

- Add note to FAQ_DEV that regression tests might need to be added.

- In developer's FAQ, update list API, from Tom Lane.

- Add FAQ item about how patches are reviewed.

- Mark TODO as done: "Allow ORDER BY ... LIMIT # to select high/low
value without sort"

Andrew Dunstan committed:

- Make clearer how arguments and return values in pl/perl are escaped.
This is to clarify the situation that Theo Schlossnagle recently
reported on -bugs.

Neil Conway committed:

- Doc tweak: add an xref to pgsql/doc/src/sgml/func.sgml.

- Fix some typos in the documentation. Patch from Brian Gough.
Backport the relevant fixes to 8.2 as well.

Alvaro Herrera committed:

- Fix a few more double words in docs.

- Use the new TimestampDifferenceExceeds API instead of
timestamp_cmp_internal and TimestampDifference, to make coding
clearer. I think this should also fix the failure to start workers
in platforms with low resolution timers, as reported by Itagaki
Takahiro.

- Fix failure to check for INVALID worker entry in the new autovacuum
code, which could happen when a worker took to long to start and was
thus "aborted" by the launcher. Noticed by lionfish buildfarm
member.

Magnus Hagander committed:

- In pgsql/src/backend/utils/adt/selfuncs.c, check return code from
strxfrm on Windows since it has a non-standard way of indicating
errors, so we don't try to allocate INT_MAX bytes to store a result
in. Per ITAGAKI Takahiro.

- Release builds generate different strangely formatted export names
for local symbols, that shouldn't be exported. This patch excludes
them, cutting down about 10,000 exported symbols and decreasing the
binary size by 20%.

- Dave Page's patch which adds a wrapper script install.bat around
install.pl that calls buildenv.bat before doing the install.

Tom Lane committed:

- Add a line to the EXPLAIN ANALYZE output for a Sort node, showing
the actual sort strategy and amount of space used. By popular
demand.

- Kazuhiro Inaoka's patch which adds tas() support for Renesas' M32R
processor.

- Suppress a recently-introduced 'variable might be clobbered by
longjmp' warning.

- A few fixups in error handling: mark pg_re_throw() as noreturn for
gcc, and for other compilers, insert a dummy exit() call so that
they understand PG_RE_THROW() doesn't return. Insert fflush(stderr)
in ExceptionalCondition, per recent buildfarm evidence that that
might not happen automatically on some platforms. And const-ify
ExceptionalCondition's declaration while at it.

- Teach tuplesort.c about "top N" sorting, in which only the first N
tuples need be returned. We keep a heap of the current best N
tuples and sift-up new tuples into it as we scan the input. For M
input tuples this means only about M*log(N) comparisons instead of
M*log(M), not to mention a lot less workspace when N is small ---
avoiding spill-to-disk for large M is actually the most attractive
thing about it. Patch includes planner and executor support for
invoking this facility in ORDER BY ... LIMIT queries. Greg Stark,
with some editorialization by moi.

- Tweak hash index AM to use the new ReadOrZeroBuffer bufmgr API when
fetching pages it intends to zero immediately. Just to show there
is some use for that function besides WAL recovery :-). Along the
way, fold _hash_checkpage and _hash_pageinit calls into _hash_getbuf
and friends, instead of expecting callers to do that separately.

- Dept. of second thoughts: add comments cautioning against using
ReadOrZeroBuffer to fetch pages from beyond physical EOF. This
would usually work, but would cause problems for md.c if writes
occurred beyond a segment boundary when the previous segment file
hadn't been fully extended.

- Heikki Linnakangas's patch which makes the following change:
During WAL recovery, when reading a page that we intend to overwrite
completely from the WAL data, don't bother to physically read it;
just have bufmgr.c return a zeroed-out buffer instead. This speeds
recovery significantly, and also avoids unnecessary failures when a
page-to-be-overwritten has corrupt page headers on disk. This
replaces a former kluge that accomplished the latter by pretending
zero_damaged_pages was always ON during WAL recovery; which was OK
when the kluge was put in, but is unsafe when restoring a WAL log
that was written with full_page_writes off.

- Fix things so that when CREATE INDEX CONCURRENTLY sets
pg_index.indisvalid true at the very end of its processing, the
update is broadcast via a shared-cache-inval message for the index;
without this, existing backends that already have relcache entries
for the index might never see it become valid. Also, force a
relcache inval on the index's parent table at the same time, so that
any cached plans for that table are re-planned; this ensures that
the newly valid index will be used if appropriate. Aside from
making C.I.C. behave more reasonably, this is necessary
infrastructure for some aspects of the HOT patch. Pavan Deolasee,
with a little further stuff from me.

- Fix oversight in PG_RE_THROW processing: it's entirely possible that
there isn't any place to throw the error to. If so, we should treat
the error as FATAL, just as we would have if it'd been thrown
outside the PG_TRY block to begin with. Although this is clearly a
potential source of bugs, it is not clear at the moment whether it
is an actual source of bugs; there may not presently be any PG_TRY
blocks in code that can be reached with no outer longjmp catcher.
So for the moment I'm going to be conservative and not back-patch
this. The change breaks ABI for users of PG_RE_THROW and hence
might create compatibility problems for loadable modules, so we
should not put it into released branches without proof that it's
needed.

- Fix a thinko in my patch of a couple months ago for bug #3116: it
did the wrong thing when inlining polymorphic SQL functions, because
it was using the function's declared return type where it should
have used the actual result type of the current call. In 8.1 and
8.2 this causes obvious failures even if you don't have assertions
turned on; in 8.0 and 7.4 it would only be a problem if the inlined
expression were used as an input to a function that did run-time
type determination on its inputs. Add a regression test, since this
is evidently an under-tested area.

- Change the timestamps recorded in transaction commit/abort xlog
records from time_t to TimestampTz representation. This provides
full gettimeofday() resolution of the timestamps, which might be
useful when attempting to do point-in-time recovery --- previously
it was not possible to specify the stop point with sub-second
resolution. But mostly this is to get rid of TimestampTz-to-time_t
conversion overhead during commit. Per my proposal of a day or two
back.

- Fix oversight in my patch of yesterday: forgot to ensure that stats
would still be forced out at backend exit.

== Abgelehnte Patches (bis jetzt) ==

No one was disappointed this week :-)

== Eingesandte Patches ==

Heikki Linnakangas sent an update of Simon's Heap Page Diagnostic
Functions.

Gavin Sherry sent in an update to his bitmap index patch.

Jaime Casanova sent in another revision of his patch which adds a GUC
for temp_tablespaces.

Dany DeBontridder sent in a patch which enables pg_dump to dump
individual objects.

Andrew Dunstan sent in a patch documenting PL/Perl's behavior with
bytea inputs.

Joachim Wieland sent in a patch which addresses the outstanding issues
of the recent guc patch.

Neil Conway sent in a patch which enables integer datetimes by
default.

Pavel Stehule sent in another revision of his patch which adds table
function support per SQL2003: T326 Table Functions.

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