== Notiziario settimanale PostgreSQL - 19 luglio 2009 ==

== Notiziario settimanale PostgreSQL - 19 luglio 2009 ==

(Traduzione parziale in lingua italiana delle PostgreSQL Weekly News a
cura di Gianni Ciolli <gianni(dot)ciolli(at)2ndquadrant(dot)it>)

È iniziata la prima Commitfest del ciclo di sviluppo per la 8.5!
http://commitfest.postgresql.org/

L'associazione ITPUG - Italian PostgreSQL Users Group si è unita al
progetto di traduzione di PostgreSQL. Un gruppo di lavoro di 10
persone ha dato inizio all'impresa di "rendere più verde" la colonna
di babel.postgresql.org dedicata alla lingua italiana. Ulteriori
informazioni in italiano a
http://traduzioni.itpug.org/

== Novità sul prodotto PostgreSQL ==

Rilasciata la versione 3.1.2 di Archiveopteryx, un sistema di gestione
per la posta elettronica basato su PostgreSQL.
http://www.archiveopteryx.org/3.1.2

Rilasciata la versione 2.9 di Benetl, uno strumento ETL per files che
usa PostgreSQL.
http://www.benetl.net

Rilasciata la versione 2.0.6 di Npgsql2, un provider di dati .NET per
PostgreSQL.
http://www.npgsql.org

Rilasciata la versione 2.5.2 di PostgreDAC.
http://microolap.com/products/connectivity/postgresdac/download/

== Offerte di lavoro su PostgreSQL per luglio 2009 ==

http://archives.postgresql.org/pgsql-jobs/2009-07/threads.php

== Notizie locali su PostgreSQL ==

Nei giorni 22 e 23 agosto 2009, a St. Augustin, in Germania, vicino a
Bonn e Colonia, si terrà OpenSQL Camp. La scadenza per presentare
comunicazioni è il 19 luglio 2009. Inviate le vostre proposte!
http://opensqlcamp.org/Events/2009/Call_for_Participation

Domenica 23 agosto 2009 il PostgreSQL User Group tedesco avrà una dev
room a FrOSCon. È aperto il Call for Papers:
http://andreas.scherbaum.la/blog/archives/573-Call-for-Papers-fuer-den-PostgreSQL-Devroom-auf-der-FrOSCon-2009.html

PyCon Argentina si terrà in Buenos Aires nei giorni 4 e 5 settembre
2009.
http://ar.pycon.org/2009/rfp/

Andreas (ads) Scherbaum terrà un corso "PostgreSQL for Corporate Use"
al centro di formazione per adulti in Magdeburgo, Germania, dal 7
all'11 settembre 2009. Trovate i dettagli qua:
http://andreas.scherbaum.la/blog/archives/574-PostgreSQL-als-Bildungsurlaub.html

Si terrà una conferenza in Athens, Georgia, USA il 19 settembre
2009. È aperto il CfP.
http://www.postgresqlconference.org/2009/pgday/athens

Si terrà una conferenza a Seattle, Washington, USA nei giorni 16-18
ottobre 2009. È aperto il CfP.
http://www.postgresqlconference.org/2009/west

È aperto il CfP per PGCon Brazil, che si svolgerà Il 23 e 24 ottobre
2009 presso Unicamp, nella città di Campinas, stato di San Paolo.
http://pgcon.postgresql.org.br/2009/chamadas.en.php

Il PGDay.EU 2009 si terrà a Telecom ParisTech in Parigi nei giorni 6 e
7 novembre 2009.
http://www.pgday.eu/

Gli organizzatori della conferenza per il decimo anniversario di JPUG
stanno accettando proposte. La conferenza si terrà i giorni 20 e 21
novembre 2009 a Tokio.
http://archives.postgresql.org/pgsql-announce/2009-05/msg00018.php

== Rassegna stampa su PostgreSQL ==

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

Questo notiziario settimanale PostgreSQL è stato realizzato da David
Fetter e Josh Berkus; traduzione parziale in lingua italiana a cura di
Gianni Ciolli.

Notizie o annunci destinati a questo notiziario dovranno pervenire
entro la mezzanotte di domenica (le 15 nel fuso orario della
California). I comunicati in lingua italiana dovranno essere inviati a
pwn(at)itpug(dot)org; per le lingue inglese o tedesca, si scriva
rispettivamente a david(at)fetter(dot)org o a pwd(at)pgug(dot)de(dot)

== Patch applicate ==

Peter Eisentraut committed:

- Update information schema to SQL:2008: Add yes_or_no domain for
"boolean" data. Add new columns for VIEWS view. Slight section
renumbering.

- Rearrangement of the HTML docs build rules. Set up proper makefile
dependencies in the documentation build rules, especially around the
HTML/index build. The problem we've had with all previous solutions
is that we have used the same file name, such as HTML.index or
bookindex.sgml, to mean different things at different stages of the
build, and make can't distinguish that. The solution here is that
the first jade run produces HTML.index, but does not require
bookindex.sgml at all, and produces no other html output (the latter
an idea from Alvaro). The second jade run includes bookindex.sgml,
but does not recreate HTML.index. That way, when you change an sgml
file, jade is run twice and at the end all dependencies are
satisfied. Omitting the html output in the first stage also makes
the full build a lot faster. When you run one of the print format
targets, only the first jade run is run, then the print
target-specific commands. If an HTML build has completed
previously, the first jade run is skipped because the dependencies
have already been satisfied. The draft and check targets for quick
builds and syntax verification are still there.

- Make backend header files C++ safe. This alters various incidental
uses of C++ key words to use other similar identifiers, so that a
C++ compiler won't choke outright. You still (probably) need extern
"C" { }; around the inclusion of backend headers. Based on a patch
by Kurt Harriman. Also add a script cpluspluscheck to check for C++
compatibility in the future. As of right now, this passes without
error for me.

Bruce Momjian committed:

- In pgsql/contrib/vacuumlo/vacuumlo.c, vacuumlo query cleanups. No
need for VACUUM ANAYZE of newly created/populated temp table, just
use analyze. No need to apologize for using subquery in DELETE
anymore.

Tom Lane committed:

- In pgsql/src/backend/utils/cache/plancache.c, do a conditional
SPI_push/SPI_pop when replanning a query in RevalidateCachedPlan.
This is to avoid a "SPI_ERROR_CONNECT" failure when the planner
calls a SPI-using function and we are already inside one. The
alternative fix is to expect callers of RevalidateCachedPlan to do
this, which seems likely to result in additional hard-to-detect bugs
of omission. Per reports from Frank van Vugt and Marek Lewczuk.
Back-patch to 8.3. It's much harder to trigger the bug in 8.3, due
to a smaller set of cases in which plans can be invalidated, but it
could happen. (I think perhaps only a SI reset event could make 8.3
fail here, but that's certainly within the realm of possibility.)

- Tweak the core scanner so that it can be used by plpgsql too.
Changes: Pass in the keyword lookup array instead of having it be
hardwired. (This incidentally allows elimination of some duplicate
coding in ecpg.) Re-order the token declarations in gram.y so that
non-keyword tokens have numbers that won't change when keywords are
added or removed. Add ".." and ":=" to the set of tokens recognized
by scan.l. (Since these combinations are nowhere legal in core SQL,
this does not change anything except the precise wording of the
error you get when you write this.)

- In pgsql/src/interfaces/ecpg/preproc/ecpg.tokens, remove duplicate
definition of TYPECAST token. (Apparently, some but not all
versions of Bison will warn about this.)

- Add erand48() to the set of functions supported by our src/port/
library, and extend configure to test for it properly instead of
hard-wiring an assumption that everybody but Windows has the rand48
functions. (We do cheat to the extent of assuming that probing for
erand48 will do for the entire rand48 family.) erand48() is unused
as of this commit, but a followon patch will cause GEQO to depend on
it. Andres Freund, additional hacking by Tom Lane.

- Make GEQO's planning deterministic by having it start from a
predictable random number seed each time. This is how it used to
work years ago, but we got rid of the seed reset because it was
resetting the main random() sequence and thus having undesirable
effects on the rest of the system. To fix, establish a private
random number state for each execution of geqo(), and initialize the
state using the new GUC variable geqo_seed. People who want to
experiment with different random searches can do so by changing
geqo_seed, but you'll always get the same plan for the same value of
geqo_seed (if holding all other planner inputs constant, of course).
The new state is kept in PlannerInfo by adding a "void *" field
reserved for use by join_search hooks. Most of the rather bulky
code changes in this commit are just arranging to pass PlannerInfo
around to all the GEQO functions (many of which formerly didn't
receive it). Andres Freund, with some editorialization by Tom Lane.

- Repair bug #4926 "too few pathkeys for mergeclauses". This example
shows that the sanity checking I added to create_mergejoin_plan() in
8.3 was a few bricks shy of a load: the mergeclauses could reference
pathkeys in a noncanonical order such as x,y,x, not only cases like
x,x,y which is all that the code had allowed for. The odd cases
only turn up when using redundant clauses in an outer join
condition, which is why no one had noticed before.

- Fix error cleanup failure caused by 8.4 changes in plpgsql to try to
avoid memory leakage in error recovery. We were calling
FreeExprContext, and therefore invoking ExprContextCallback
callbacks, in both normal and error exits from subtransactions.
However this isn't very safe, as shown in recent trouble report from
Frank van Vugt, in which releasing a tupledesc refcount failed.
It's also unnecessary, since the resources that callbacks might wish
to release should be cleaned up by other error recovery mechanisms
(ie the resource owners). We only really want FreeExprContext to
release memory attached to the exprcontext in the error-exit case.
So, add a bool parameter to FreeExprContext to tell it not to call
the callbacks. A more general solution would be to pass the
isCommit bool parameter on to the callbacks, so they could do only
safe things during error exit. But that would make the patch
significantly more invasive and possibly break third-party code that
registers ExprContextCallback callbacks. We might want to do that
later in HEAD, but for now I'll just do what seems reasonable to
back-patch.

- Fix a thinko in join_is_legal: when we decide we can implement a
semijoin by unique-ifying the RHS and then inner-joining to some
other relation, that is not grounds for violating the RHS of some
other outer join. Noticed while regression-testing new GEQO code,
which will blindly follow any path that join_is_legal says is legal,
and then complain later if that leads to a dead end. I'm not
certain that this can result in any visible failure in 8.4: the
mistake may always be masked by the fact that subsequent attempts to
join the rest of the RHS of the other join will fail. But I'm not
certain it can't, either, and it's definitely not operating as
intended. So back-patch. The added regression test depends on the
new no-failures-allowed logic that I'm about to commit in GEQO, so
no point back-patching that.

- Rewrite GEQO's gimme_tree function so that it always finds a legal
join sequence, even when the input "tour" doesn't lead directly to
such a sequence. The stack logic that was added in 2004 only
supported cases where relations that had to be joined to each other
(due to join order restrictions) were adjacent in the tour.
However, relying on a random search to figure that out is
tremendously inefficient in large join problems, and could even fail
completely (leading to "failed to make a valid plan" errors) if
random_init_pool ran out of patience. It seems better to make the
tour-to-plan transformation a little bit fuzzier so that every tour
can form a legal plan, even though this means that apparently
different tours will sometimes yield the same plan. In the same
vein, get rid of the logic that knew that tours (a,b,c,d,...) are
the same as tours (b,a,c,d,...), and therefore insisted the latter
are invalid. The chance of generating two tours that differ only in
this way isn't that high, and throwing out 50% of possible tours to
avoid such duplication seems more likely to waste valuable genetic-
refinement generations than to do anything useful. This leaves us
with no cases in which geqo_eval will deem a tour invalid, so get
rid of assorted kluges that tried to deal with such cases, in
particular the undocumented assumption that DBL_MAX is an impossible
plan cost. This is all per testing of Robert Haas'
lets-remove-the-collapse-limits patch. That idea has crashed and
burned, at least for now, but we still got something useful out of
it. It's possible we should back-patch this change, since the
"failed to make a valid plan" error can happen in existing releases;
but I'd rather not until it has gotten more testing.

- Teach simplify_boolean_equality to simplify the forms foo <> true
and foo <> false, along with its previous duties of simplifying foo
= true and foo = false. (All of these are equivalent to just foo or
NOT foo as the case may be.) It's not clear how often this is
really useful; but it costs almost nothing to do, and it seems some
people think we should be smart about such cases. Per recent bug
report.

- In pgsql/src/bin/psql/describe.c, remove unnecessary and
version-sensitive dependence on the exact set of column names to be
found in a sequence. Per gripe from Bruce Momjian.

Heikki Linnakangas committed:

- In pgsql/contrib/pg_standby/Makefile, pg_standby doesn't need to be
linked with libpq. Fujii Masao.

Andrew Dunstan committed:

- DROP IF EXISTS for columns and constraints. Andres Freund.

== Patch rifiutate (per adesso) ==

No one was disappointed this week :-)

== Patch in coda ==

Heikki Linnakangas sent in two revisions of a patch which helps set up
index-only scans.

Robert Haas sent in an updated patch for Hot Standby.

Petr (PJMODOS) Jelinek sent in three revisions of a patch to add
DefaultACLs
http://wiki.postgresql.org/wiki/DefaultACL

ITAGAKI Takahiro sent in two revisions of a patch to add FORCE QUOTE
to COPY...CSV.

KaiGai Kohei sent in three more revisions of his SE-PostgreSQL patch.

Jeff Davis sent in another revision of his patch to make more
generalized constraints.

Andres Freund sent in a patch to refactor *_collapse_limit and
geqo_threshold.

Jaime Casanova sent in a revision of Taro (higepon) Minowa's patch to
allow pg_dump* to dump comments on commposite-type and index columns.

ITAGAKI Takahiro sent in an update for the sampling profiler patch.

Tsutomu Yamada sent in two revisions of a patch to fix the ""could not
reattach to shared memory" bug on Windows.

Fujii Masao sent in two more revisions of the Synchronous Replication
patch.

Oleg Bartunov sent in a patch which adds prefix support for synonym
dictionaries in full-text search.

Oleg Bartunov sent in a patch to add filtering dictionaries and a new
contrib module, unaccent, which removes accents, using same.

Sergey V. Karpov sent in a patch which extends the functionality of
dict_xsyn extended synonym dictionary.

Fernando Ike de Oliveira sent in two revisions of a patch to add \dL
for PL languages to psql.

Zoltan Boszormenyi sent in another revision of his patch set to
improve ECPG's Informix compatibility layer.

Tom Lane sent in a WIP patch to make PL/pgsql use the core lexer.

Caleb Welton sent in another revision of his patch to add bytea to
PL/PythonU.

Andrew (RhodiumToad) Gierth sent in another revision of the hstore
patch with fixes and new tests for some edge case bugs.

Kevin Grittner sent in a patch to revise parallel pg_restore's
scheduling heuristic.

Steve Prentice sent in another revision of the patch to make PL/pgsql
treat any word following AS as a label.

Petr (PJMODOS) Jelinek sent in two revisions of a patch to implement
GRANT ON ALL IN schema.

Richard Huxton sent in a patch to create a navigation menu for the
documentation.

Fujii Masao sent in another revision of the patch to multiplex
SIGUSR1, which is infrastructure for the Synchronous Replication
feature.

Zoltan Boszormenyi sent in a patch to add struct support for SELECT
INTO to ECPG.

Peter Eisentraut sent in a patch to make PL/Python use errcontext()
instead of passing the function names around to use in error messages.

Alan Li sent in a patch to optimize MIN and MAX queries on partitioned
tables.

Andreas Wenk sent in a patch to include the \du+ option in \? output
in psql.

Bernd Helmle sent in a revision of Pavel Stehule's patch to allow
mixed and named notation support for PL/pgsql functions.

Dean Rasheed sent in another revision of the deferrable UNIQUE
constraints patch.

Jeremy Kerr sent in another revision of the patch to avoid manual
shift-and-test logic in AllocSetFreeIndex.

Andreas Freund sent in another revision of his patch to allow
machine-readable EXPLAIN output.

Andreas Freund sent in two more revisions of his generic EXPLAIN
options patch.