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Wöchentlicher PostgreSQL Newsletter - 18. Februar 2007


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

== Wöchentlicher PostgreSQL Newsletter - 18. Februar 2007 ==

Version 3.4 des Open Source SYMBOL Australian Accountingprogramms enthält erweiterte Skalierbarkeit für PostgreSQL.
http://www.pcworld.idg.com.au/index.php/id;1504289875

IGN, das Französische Nationale Geografie Institut, hat PostgreSQL und PostGIS aufgrund der Skalierbarkeit, der Geschwindugkeit und der Transaktionssicherheit gewählt.
http://postgis.refractions.net/documentation/casestudies/ign/

== PostgreSQL Produkt Neuigkeiten ==

pgmemcache 1.1 erschienen. Fortlaufende Entwicklung wird von der Opten Technology Group, Inc. gesponsert.
http://pgfoundry.org/projects/pgmemcache/

pgchem::tigress 7.0 erschienen.
http://pgfoundry.org/projects/pgchem/

pgpool-II 1.0.2 erschienen.
http://pgfoundry.org/projects/pgpool/

PL/PgPSM 0.2.0 erschienen, jetzt mit voller SQL/PSM Unterstützung. Es ist wie jedes andere contrib Paket mit PGXS installierbar.
http://pgfoundry.org/projects/plpsm/

== PostgreSQL Jobs im Februar ==

http://archives.postgresql.org/pgsql-jobs/2007-02/threads.php

== PostgreSQL Lokal ==

Es wird einen PostgreSQL Stand auf dem CLT am 3.-4. März in Chemnitz/Deutschland geben. Einige der üblichen Verdächtigen der deutschsprachigen PostgreSQl Community werden dort sein. Kontaktiere info@pgug.de für mehr Informationen.
http://chemnitzer.linux-tage.de/2007/info/

Es wird einen PostgreSQL Stand auf der FOSDEM am 24. und 25. Februar in Brüssel, Belgien sein. Viele der üblichen Verdächtigen von den EU PostgreSQL Communities werden dort sein. Kontaktiere de@postgresql.org für mehr Informationen.
http://www.fosdem.org/2007/

Die italienische PostgreSQL Community ist auf der Suche nach Sponsoren für ihren PostgreSQL Tag in Prato, Italien im Sommer. Mehr Informationen unter untenstehendem Link.
http://www.pgday.it

== 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, Jean-Paul Argudo and Josh Berkus.

Um deine Beiträge für die nächste Ausgabe zu übermitteln, sende diese an david@fetter.org bis Sonntag, 15:00 Uhr Pazifischer Zeit.

== Angewandte Patches ==

Alvaro Herrera committed:

- Install a more correct fix in the timestamp and timestamptz
regression tests: remove duplicated tests in timestamp, and complete
timestamptz with the tests that were missing to more closely mirror
timestamp.

- Fix the timestamptz test problem, by moving the tests that use the
timestamp_tbl table into the timestamp test. Also, restore a test
that used to exist as a valid test in the timestamptz test.

- Remove useless database name from bootstrap argument processing
(including startup and bgwriter processes), and the -y flag. It's
not used anywhere.

- Restructure autovacuum in two processes: a dummy process, which runs
continuously, and requests vacuum runs of "autovacuum workers" to
postmaster. The workers do the actual vacuum work. This allows for
future improvements, like allowing multiple autovacuum jobs running
in parallel. For now, the code keeps the original behavior of
having a single autovac process at any time by sleeping until the
previous worker has finished.

Peter Eisentraut committed:

- Better fix for determining minimum and maximum int64 values that
doesn't require stdint.h and works for "busted" int64.

- Remove naughty // comment from pgsql/src/backend/utils/adt/formatting.c

- Add stdint.h header to pgsql/src/backend/utils/adt/xml.c

- Add functions for mapping table data and table schemas to XML
(a.k.a. XML export)

- Fix typo in pgsql/doc/src/sgml/func.sgml.

Neil Conway committed:

- Fix capitalization and punctuation of two more GUC description
strings.

Magnus Hagander committed:

- Make it possible to build with integer datetimes in msvc, and enable
by default.

- Un-break build on ANSI compilers (like msvc) by moving Assert to
position after variable declarations.

- Add script to run regression tests under vc++ without mingw. Update
clean script to properly clean up the result of it.

- One more fix for makefile := to : change.

- Properly parse Makefile after change from := to =.

Bruce Momjian committed:

- In pgsql/doc/src/sgml/spi.sgml, document that when sending multiple
commands in a single string to SPI_execute(), the later commands
cannot depend on the creation of objects earlier in the string.

- Update wording in TODO with some commas.

- Add to TODO: "Allow SQL-language functions to reference parameters
by parameter name." currently SQL-language functions can only refer
to parameters via $1, etc

- Update "Conflicting lock modes" to show as conflict, add
current/requested headings, add link to table from text.

- Remove rint() for to_char MS and US output. We can't us rint()
because we can't overflow to the next higher units, and we might
print the lower units for MS.

- Add to TODO: "Allow holdable cursors in SPI."

- Cleanup of Brendan Jurd's to_char() patch.

- Add to TODO: "Allow row and record variables to be set to NULL
constants, and allow NULL tests on such variables Because a row is
not scalar, do not allow assignment from NULL-valued scalars.

- Remove installation mention that integer timestamps is less stable
that floating point.

- Mark Kirkwood's patch to create AVG() aggregates for int8 and
NUMERIC which do not compute X^2, as a performance enhancement.

- Add to TODO: "Consider reducing on-disk varlena length from four to
two because a heap row cannot be more than 64k in length

- Reduce the amount of memory "clobbered" for every process title
change, on platforms that need this. This is done by only writing
past the previously stored message, if it was longer.

- In pgsql/doc/src/sgml/ecpg.sgml, remove extra character erroneously
added.

- Remove tabs from SGML files to help tag alingment and improve
detection of tabs are added in the future.

- Brendan Jurd's patch which adds two new format fields for use with
to_char(), to_date() and to_timestamp() "ID" for day-of-week and
"IDDD" for day-of-year This makes it possible to convert ISO week
dates to and from text fully represented in either week
('IYYY-IW-ID') or day-of-year ('IYYY-IDDD') format. It also adds an
'isoyear' field for use with extract / date_part.

- Victor B. Wagner's SSL improvements which allow reading a global SSL
configuration file, add GUC "ssl_ciphers" to control allowed
ciphers, and add libpq environment variable PGSSLKEY to control SSL
hardware keys

- Add to TODO: "Use LC_TIME for localized weekday/month names, rather
than LC_MESSAGES."

- Fix to_date()/to_timestamp() 'D' field for day of week, was off by
one. Converting from char using 'D' doesn't make lots of sense, of
course. Report from Brendan Jurd.

- Move fsync method macro defines into /include/access/xlogdefs.h so
they can be used by src/tools/fsync/test_fsync.c.

- Add to TODO: "Clean up casting in /contrib/isn."

- Add to TODO: "Improve logging of prepared statements recovered
during startup."

- In TODO, add URL for, "Allow SQL-language functions to return
results from RETURNING queries."

- In TODO, add URL for, "Allow accurate statistics to be collected on
indexes with more than one column or expression indexes, perhaps
using per-index statistics."

- In TODO, add URL for, "Update Bonjour to work with newer
cross-platform SDK"

- Add to TODO: "Improve failure message when DROP DATABASE is used on
a database that has prepared transactions."

- In TODO, add URL for, "Update Bonjour to work with newer
cross-platform SDK."

- In clusterdb and reindexdb, add code so database scans are done in
an order consistent with pg_dumpall.

- Update /contrib/fuzzystrmatch error message to mention bytes, not
just 'length', which can be characters.

- Add ORDER BY to vacummdb so databases are scaned in the same order
as pg_dumpall.

- Add to TODO: "Update our code to handle 64-bit timezone files to
match the zic source code, which now uses them"

- In pgsql/src/port/open.c, add comment to explain why O_EXCL and
O_TRUNC can be ignored in openFlagsToCreateFileFlags() in certain
cases.

- In pgsql/src/backend/utils/adt/formatting.c, add comment that
to_char() for broken glibc pt_BR might cause a problem.

Tom Lane committed:

- Improve plpgsql's error message when a datatype declaration is
omitted. Per example from Jeff Ross.

- Put function expressions and values lists into FunctionScan and
ValuesScan plan nodes, so that the executor does not need to get
these items from the range table at runtime. This will avoid
needing to include these fields in the compact range table I'm
expecting to make the executor use.

- Fix portal management code to support non-default command completion
tags for portals using PORTAL_UTIL_SELECT strategy. This is
currently significant only for FETCH queries, which are supposed to
include a count in the tag. Seems it's been broken since 7.4, but
nobody noticed before Knut Lehre.

- Add code so that when COPY_PARSE_PLAN_TREES is defined, the copy and
equal functions are checked for raw parse trees as well as
post-analysis trees. This was never very important before, but the
upcoming plan cache control module will need to be able to do
copyObject() on raw parse trees.

- Teach find_nonnullable_rels to handle OR cases: if every arm of an
OR forces a particular relation nonnullable, then we can say that
the OR does. This is worth a little extra trouble since it may
allow reduction of outer joins to plain joins.

- Fix new RI operator selection code to do the right thing when
working with an opclass for a generic type such as ANYARRAY. The
original coding failed to check that PK and FK columns were of the
same array type. Per discussion with Tom Dunstan. Also, make the
code a shade more readable by not trying to economize on variables.

- Adjust the definition of is_pushed_down so that it's always true for
INNER JOIN quals, just like WHERE quals, even if they reference
every one of the join's relations. Now that we can reorder outer
and inner joins, it's possible for such a qual to end up being
assigned to an outer join plan node, and we mustn't have it treated
as a join qual rather than a filter qual for the node. (If it were,
the join could produce null-extended rows that it shouldn't.) Per
bug report from Pelle Johansson.

- Code review for SSLKEY patch.

- Fix markup, spelling, grammar, and explanations for SSLKEY patch.

- Fix another problem in 8.2 changes that allowed "one-time" qual
conditions to be checked at plan levels below the top; namely, we
have to allow for Result nodes inserted just above a nestloop inner
indexscan. Should think about using the general Param mechanism to
pass down outer-relation variables, but for the moment we need a
back-patchable solution. Per report from Phil Frost.

- Restructure code that is responsible for ensuring that clauseless
joins are considered when it is necessary to do so because of a
join-order restriction (that is, an outer-join or IN-subselect
construct). The former coding was a bit ad-hoc and inconsistent,
and it missed some cases, as exposed by Mario Weilguni's recent bug
report. His specific problem was that an IN could be turned into a
"clauseless" join due to constant-propagation removing the IN's
joinclause, and if the IN's subselect involved more than one
relation and there was more than one such IN linking to the same
upper relation, then the only valid join orders involve "bushy"
plans but we would fail to consider the specific paths needed to get
there. (See the example case added to the join regression test.)
On examining the code I wonder if there weren't some other problem
cases too; in particular it seems that GEQO was defending against a
different set of corner cases than the main planner was. There was
also an efficiency problem, in that when we did realize we needed a
clauseless join because of an IN, we'd consider clauseless joins
against every other relation whether this was sensible or not. It
seems a better design is to use the outer-join and in-clause lists
as a backup heuristic, just as the rule of joining only where there
are joinclauses is a heuristic: we'll join two relations if they
have a usable joinclause *or* this might be necessary to satisfy an
outer-join or IN-clause join order restriction. I refactored the
code to have just one place considering this instead of three, and
made sure that it covered all the cases that any of them had been
considering. Backpatch as far as 8.1 (which has only the IN-clause
form of the disease). By rights 8.0 and 7.4 should have the bug
too, but they accidentally fail to fail, because the joininfo
structure used in those releases preserves some memory of there
having once been a joinclause between the inner and outer sides of
an IN, and so it leads the code in the right direction anyway. I'll
be conservative and not touch them.

- Add ORDER BY to a query on information_schema.views, to avoid
possible platform-specific result ordering. Per buildfarm results.

- Repair oversight in 8.2 change that improved the handling of
"pseudoconstant" WHERE clauses. createplan.c is now willing to
stick a gating Result node almost anywhere in the plan tree, and in
particular one can wind up directly underneath a MergeJoin node.
This means it had better be willing to handle Mark/Restore.
Fortunately, that's trivial in such cases, since we can just pass
off the call to the input node (which the planner has previously
ensured can handle Mark/Restore). Per report from Phil Frost.

- Add some discussion of sort ordering to indices.sgml, which
curiously had never touched the subject before.

- Heikki Linnakangas's patch which throws an error if you try to
COMMIT/ROLLBACK PREPARED from a database other than the one where
the transaction was originally prepared.

- Minor editorialization on operator-family documentation: put some
copied-and-pasted text in a more useful location.

- Fix up foreign-key mechanism so that there is a sound semantic basis
for the equality checks it applies, instead of a random dependence
on whatever operators might be named "=". The equality operators
will now be selected from the opfamily of the unique index that the
FK constraint depends on to enforce uniqueness of the referenced
columns; therefore they are certain to be consistent with that
index's notion of equality. Among other things this should fix the
problem noted awhile back that pg_dump may fail for foreign-key
constraints on user-defined types when the required operators aren't
in the search path. This also means that the former warning
condition about "foreign key constraint will require costly
sequential scans" is gone: if the comparison condition isn't
indexable then we'll reject the constraint entirely. All per past
discussions. Along the way, make the RI triggers look into
pg_constraint for their information, instead of using
pg_trigger.tgargs; and get rid of the always error-prone fixed-size
string buffers in ri_triggers.c in favor of building up the RI
queries in StringInfo buffers. This forces initdb due to columns
added to pg_constraint and pg_trigger.

- Disallow committing a prepared transaction unless we are in the same
database it was executed in. Someday it might be nice to allow
cross-DB commits, but work would be needed in NOTIFY and perhaps
other places. Per Heikki Linnakangas.

- Improve postmaster's behavior if an accept() call fails. Because
the server socket is still read-ready, the code was a tight loop,
wasting lots of CPU. We can't do anything to clear the failure,
other than wait, but we should give other processes more chance to
finish and release FDs; so insert a small sleep. Also, avoid bogus
"close(-1)" in this case. Per report from Jim Nasby.

- Repair bug in 8.2's new logic for planning outer joins: we have to
allow joins that overlap an outer join's min_righthand but aren't
fully contained in it, to support joining within the RHS after
having performed an outer join that can commute with this one.
Aside from the direct fix in make_join_rel(), fix
has_join_restriction() and GEQO's desirable_join() to consider this
possibility. Per report from Ian Harding.

- Avoid infinite recursion when dumping new planner EquivalenceClass
trees.

Teodor Sigaev committed:

- Fix backend crash in parsing incorrect tsquery. Per report from Jon
Rosebaugh.

== Abgelehnte Patches (bis jetzt) ==

No one was disappointed this week :-)

== Eingesandte Patches ==

Pavel Stehule sent in a patch which implements TABLE functions per
SQL:2003.

Greg Smith sent in a patch which adds two command-line switches to
pgbench: -x, which generates extended detail in the latency log, and
-X, which does extra cleanup work after the run.

Pavan Deolasee sent in another version of the HOT-update patch.

Gregory Stark sent in a patch to replace the VARATT_SIZEP with
SET_VARLENA_LEN. This is part of the implementation of the
variable-length varlena type per discussion on -hackers.

Tom Dunstan sent in an updated version of his enums patch.

Magnus Hagander sent in a patch to support MOVE for cursors in
PL/PgSQL.

Arul Shaji sent in a patch to implement the TODO item, "Allow server
log information to be output as INSERT statements
This would allow server log information to be easily loaded into a
database for analysis." Tom Lane suggested that he refactor this as
COPY statements.

Alvaro Herrera sent in two more patches to clean up the bootstrap
code.

Chad Wagner sent in a patch which allows psql's \pset to take an
argument for boolean variables. The old toggling behavior still works
when no argument is passed.

Bruce Momjian sent in a patch implementing isodow in date_part.
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