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== Postgres Weekly News - 20 aprile 2008 ==

From: rotellaro(at)gmail(dot)com
To: pgsql-it-generale <pgsql-it-generale(at)postgresql(dot)org>, itpug(at)lists(dot)itpug(dot)org, itpug-soci(at)lists(dot)itpug(dot)org
Subject: == Postgres Weekly News - 20 aprile 2008 ==
Date: 2008-04-21 06:32:54
Message-ID: a3e8e2210804202332q8f1c335ic217e5605befa5d2@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-it-generale
Molte patch stanno arrivando sulla lista -patches.
Lo stand di PostgreSQL al FISL è stato un'altro successo, questa volta
con una nuova veste orientata all'addestramento, nuove facce nello
staff e qualche tragedia alla fine.
Il FISL ha totalizzato quasi 7500 partecipanti quest'anno diventando
la più grande conferenza FLOSS.


== Postgres News prodotti ==
Rilasciato Archiveopteryx 2.08.
http://www.archiveopteryx.org/2.08

Il corso sul PITR di Federico (rotellaro) Campoli ci sarà il 9 giugno 2008.
http://www.pghost.eu/node/59

== Offerte di lavoro legate a PostgreSQL per il mese di Aprile ==
http://archives.postgresql.org/pgsql-jobs/2008-04/threads.php

== PostgreSQL news locali ==

L'Unicamp PostgreSQL Day  2008 ci sara' il 22 aprile a Campinas, SP, Brasile.
http://www.dextra.com.br/dia-postgresql.htm

Il Corporate Databases 2008 ci sarà il 24 e 25 aprile a Mosca.
http://citforum.ru/seminars/cbd2008/

Il PGCon 2008 ci sarà dal 20 al 23 maggio a Ottawa.
http://www.pgcon.org/2008/

Il PGDay ci sarà a Portland il giorno precedente all'OSCON.
http://pugs.postgresql.org/taxonomy/term/53

La conferenza Open Source 2008 dello stato dell'Utah ha aperto il call
for paper fino al primo giugno.
Questa seconda conferenza annuale ci sarà dal 28 al 30 agosto a Salt Lake City
http://2008.utosc.com/

== News su PostgreSQL ==

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

General Bits, archivi e nuovi articoli occasionali:
http://www.varlena.com/GeneralBits/

PostgreSQL Weekly News è stato spedito questa settimana grazie a David Fetter.

Per segnalare news e annunci invia un email in inglese entro le ore 15,
fuso orario della costa orientale degli U.S.A, di domenica.

Per segnalazioni in inglese david(at)fetter(dot)org, per segnalazioni in
Tedesco pwn(at)pgug(dot)de, per segnalazioni in italiano pwn(at)itpug(dot)org


== Patch applicate ==
Tom Lane committed:

- Push index operator lossiness determination down to GIST/GIN opclass
 "consistent" functions, and remove pg_amop.opreqcheck, as per recent
 discussion.  The main immediate benefit of this is that we no longer
 need 8.3's ugly hack of requiring @@@ rather than @@ to test
 weight-using tsquery searches on GIN indexes.  In future it should
 be possible to optimize some other queries better than is done now,
 by detecting at runtime whether the index match is exact or not.
 Tom Lane, after an idea of Heikki Linnakangas's, and with some help
 from Teodor Sigaev.

- In pgsql/src/backend/utils/cache/relcache.c, fix LOAD_CRIT_INDEX()
 macro to take out AccessShareLock on the system index it is trying
 to build a relcache entry for.  This is an oversight in my 8.2 patch
 that tried to ensure we always took a lock on a relation before
 trying to build its relcache entry.  The implication is that if
 someone committed a reindex of a critical system index at about the
 same time that some other backend were starting up without a valid
 pg_internal.init file, the second one might PANIC due to not seeing
 any valid version of the index's pg_class row.  Improbable case, but
 definitely not impossible.

- Repair two places where SIGTERM exit could leave shared memory state
 corrupted.  (Neither is very important if SIGTERM is used to shut
 down the whole database cluster together, but there's a problem if
 someone tries to SIGTERM individual backends.)  To do this,
 introduce new infrastructure macros
 PG_ENSURE_ERROR_CLEANUP/PG_END_ENSURE_ERROR_CLEANUP that take care
 of transiently pushing an on_shmem_exit cleanup hook.  Also use this
 method for createdb cleanup --- that wasn't a
 shared-memory-corruption problem, but SIGTERM abort of createdb
 could leave orphaned files lying around.  Backpatch as far as 8.2.
 The shmem corruption cases don't exist in 8.1, and the createdb
 usage doesn't seem important enough to risk backpatching further.

- In pgsql/src/backend/commands/explain.c, add some code to EXPLAIN to
 show the targetlist (ie, output columns) of each plan node.  For the
 moment this is debug support only and is not enabled unless
 EXPLAIN_PRINT_TLISTS is defined at build time.  Later I'll see about
 the idea of letting EXPLAIN VERBOSE do it.

- Fix a couple of oversights associated with the "physical tlist"
 optimization: we had several code paths where a physical tlist could
 be used for the input to a Sort node, which is a dumb idea because
 any unneeded table columns will increase the volume of data the sort
 has to push around.  (Unfortunately the easy-looking fix of calling
 disuse_physical_tlist during make_sort_xxx doesn't work because in
 most cases we're already committed to the current input tlist ---
 it's been marked with sort column numbers, or we've built grouping
 column numbers using it, etc.  The tlist has to be selected properly
 at the calling level before we start constructing sort-col
 information.  This is easy enough to do, we were just failing to
 take the point into consideration.) Back-patch to 8.3.  I believe
 the problem probably exists clear back to 7.4 when the physical
 tlist optimization was added, but I'm afraid to back-patch further
 than 8.3 without a great deal more study than I want to put into it.
 The code in this area has drifted a lot over time.  The real-world
 importance of these code paths is uncertain anyway --- I think in
 many cases we'd probably prefer hash-based methods.

- Cause EXPLAIN's VERBOSE option to print the target list (output
 column list) of each plan node, instead of its former behavior of
 dumping the internal representation of the plan tree.  The latter
 display is still available for those who really want it (see
 debug_print_plan), but uses for it are certainly few and and far
 between.  Per discussion.  This patch also removes the
 explain_pretty_print GUC, which is obsoleted by the change.

- Fix rmtree() so that it keeps going after failure to remove any
 individual file; the idea is that we should clean up as much as we
 can, even if there's some problem removing one file.  Make the error
 messages a bit less misleading, too.  In passing, const-ify function
 arguments.

- Fix typo in pgsql/contrib/seg/uninstall_seg.sql.

- In pgsql/contrib/seg/seg.c, seg_size() has to be V1 calling
 convention, too.

- In pgsql/contrib/earthdistance/earthdistance.c, convert
 earthdistance's only C function to v1 call convention,
 to future-proof it against pass-by-value float8.

- Allow float8, int8, and related datatypes to be passed by value on
 machines where Datum is 8 bytes wide.  Since this will break
 old-style C functions (those still using version 0 calling
 convention) that have arguments or results of these types, provide a
 configure option to disable it and retain the old pass-by-reference
 behavior.  Likewise, provide a configure option to disable the
 recently-committed float4 pass-by-value change.  Zoltan Boszormenyi,
 plus configurability stuff by me.

- Make earthdistance use version-0 calling convention if not
 USE_FLOAT8_BYVAL, and version-1 if USE_FLOAT8_BYVAL.  This might
 seem a bit pointless, but the idea is to have at least one
 regression test that will fail if we ever accidentally break
 version-0 functions that return float8.  However, they're already
 broken, or at least hopelessly unportable, in the USE_FLOAT8_BYVAL
 case.  Per a recent suggestion from Greg Stark.

- In pgsql/src/include/pg_config.h.win32, add
 FLOAT4PASSBYVAL/FLOAT8PASSBYVAL to pg_config.h.win32, as a stopgap
 measure to get the Windows buildfarm members working again.  I don't
 know if it's worth exposing these as configurables, or exactly how
 to do it in the MSVC build system ...

- In pgsql/src/backend/executor/execMain.c, fix a couple of places in
 execMain that erroneously assumed that SELECT FOR UPDATE/SHARE
 couldn't occur as a subquery in a query with a non-SELECT top-level
 operation.  Symptoms included outright failure (as in report from
 Mark Mielke) and silently neglecting to take the requested row
 locks.  Back-patch to 8.3, because the visible failure in the INSERT
 ...  SELECT case is a regression from 8.2.  I'm a bit hesitant to
 back-patch further given the lack of field complaints.

Alvaro Herrera committed:

- In pgsql/src/bin/psql/describe.c, fix indentation in new REFERENCED
 BY psql output, per Brendan Jurd.

- Clean up a few places where Datums were being treated as pointers
 (and vice versa) without going through DatumGetPointer.  Gavin
 Sherry, with Feng Tian.

- Modify the float4 datatype to be pass-by-val.  Along the way, remove
 the last uses of the long-deprecated float32 in contrib/seg; the
 definitions themselves are still there, but no longer used.
 fmgr/README updated to match.  I added a CREATE FUNCTION to account
 for existing seg_center() code in seg.c too, and some tests for it
 and the neighbor functions.  At the same time, remove checks for
 NULL which are not needed (because the functions are declared
 STRICT).  I had to do some adjustments to contrib's btree_gist too.
 The choices for representation there are not ideal for changing the
 underlying types :-(  Original patch by Zoltan Boszormenyi, with
 some adjustments by me.

- In pgsql/contrib/seg/seg.c, change the float4-returning functions in
 contrib/seg to fmgr v1 calling conventions.  I also changed seg_in
 and seg_out, which was probably unnecessary, but it can't harm.

Bruce Momjian committed:

- Add URL for TODO: "Consider automatic caching of statements at
 various levels."

- Add pg_terminate_backend() to allow terminating only a single
 session.

- Mark TODO as DONE: "Allow administrators to safely terminate
 individual sessions."

- Add to TODO: "Allow XML to accept more liberal DOCTYPE
 specifications."

- Move LISTEN/NOTIFY items to separate TODO section.

- Split TODO into two items: "Allow NOTIFY in rules involving
 conditionals" and "Improve LISTEN concurrency."

- Revert addition of pg_terminate_backend() because of race
 conditions.  Unmark TODO.

- Re-add terminate TODO item.

- Add to TODO: "Implement the non-threaded Avahi service discovery
 protocol."

- Update TODO wording on psql.

- In pgsql/src/bin/psql/mbprint.c, fix comment typo.  Bryce Nesbitt.

- In FAQ, update most recent release to 8.3.1.

- In pgsql/src/tools/pgindent/pgindent, ignore blank lines in typedef
 file.

- Re-enable pg_terminate_backend() using SIGTERM.  SIGTERM testing
 still needed.

- Mark TODO as DONE: "Allow administrators to safely terminate
 individual sessions."

- Remove TODO.detail references;  instead add TODO URLs pointing to
 the archives.  We have been using URLs for a while for new items.

- Remove TODO.detail directory.  All URLs now in TODO file as
 references.

- Update TODO using new script.

- Add TODO2html tool to convert TODO to HTML.

- Add script FAQ2txt to convert HTML files to txt.  Add comment to
 TODO2html.

- Update doc script comments.

Andrew Dunstan committed:

- Make integer_datetimes the default for MSVC even if not mentioned in
 config.pl.

-  In pgsql/src/tools/msvc/Project.pm, add multi-line flag to regex
  that needs it. Backpatch to 8.2.  Fix from Andreas Zeugswetter.

- Avoid using unnecessary pgwin32_safestat in libpq.

- Fix MinGW warnings re: formats and unused variables.  Per ITAGAKI
 Takahiro.

Heikki Linnakangas committed:

- Fix two race conditions between the pending unlink mechanism that
 was put in place to prevent reusing relation OIDs before next
 checkpoint, and DROP DATABASE. First, if a database was dropped,
 bgwriter would still try to unlink the files that the rmtree() call
 by the DROP DATABASE command has already deleted, or is just about
 to delete. Second, if a database is dropped, and another database is
 created with the same OID, bgwriter would in the worst case delete a
 relation in the new database that happened to get the same OID as a
 dropped relation in the old database.  To fix these race conditions:
 1. make rmtree() ignore ENOENT errors. This fixes the 1st race
 condition.  2.  make ForgetDatabaseFsyncRequests forget unlink
 requests as well.  3. force checkpoint on in dropdb on all platforms
 Since ForgetDatabaseFsyncRequests() is asynchronous, the 2nd change
 isn't enough on its own to fix the problem of dropping and creating
 a database with same OID, but forcing a checkpoint on DROP DATABASE
 makes it sufficient.  Per Tom Lane's bug report and proposal.
 Backpatch to 8.3.

Teodor Sigaev committed:

- In pgsql/src/backend/utils/adt/tsquery_gist.c, fix broken compare
 function for tsquery_ops. Per Tom Lane's report.  I never understood
 why initial authors GiST in pgsql choose so stgrange signature for
 'same' method: bool *sameFn(Datum a, Datum b, bool* result) instead
 of simple, logical bool sameFn(Datum a, Datum b) This change will
 break any existing GiST extension, so we still live with it and will
 live.

== Patch rigettate (per ora) ==

Nessuno e' stato scontentato questa settimana :-)

== Patch in attesa ==

Brendan Jurd sent in another revision of his printTable API.

Alvaro Herrera sent in another revision of his patch to track
ActiveSnapshot.

Bruce Momjian and Bryce Nesbitt updated Bryce Nesbitt's patch in
several iterations.  The patch optionally sets a maximum width for
psql output and wraps the overflow.

Brendan Jurd sent in a new revision of his patch to show INHERIT in
\du.

Brendan Jurd sent in a new revision of his patch to add conversions
Text <-> C string.

Tom Lane sent in a WIP patch to remove lossy-operator RECHECK flags in
some places.

Teodor Sigaev sent in another revision of a patch which implements
partial match in GIN indexes.

Merlin Moncure sent in a patch to add hooks for the libpqtypes
proposal.

ITAGAKI Takahiro sent in a patch which sorts writes during a
checkpoint.

Brendan Jurd sent in a patch to remove the typename field from
A_Const.

Merlin Moncure sent in a patch to add PQmakeResult, PQsetValue and
PQresultAlloc to libpq.

Andrew Chernow sent in two revisions of his libpq object hooks patch.

Pavel Stehule sent in a patch which adds new options (SQLSTATE,
DETAIL, DETAIL_LOG and HINT) to PL/PgSQL's RAISE statement.

Alex Hunsaker sent in a revised version of Joshua Drake's patch which
adds a command line option --use-statement-timeout to pg_dump and
pg_restore.

Brendan Jurd sent in two revisions of a patch which makes \z
privileges multi-line in psql.

-- 
(all opinions expressed are my own)
Federico Campoli
PostgreSQL Consulting -> PGHost http://www.pghost.eu

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