Notiziario settimanale PostgreSQL – 3 giugno 2012

I rilasci di sicurezza 9.1.4, 9.0.8, 8.4.12 e 8.3.19, che correggono un problema con la versione FreeBSD di crypt() (insieme ad altre cose), saranno disponibili a breve. Preparatevi ad aggiornare! Per informazioni:

Novità sul prodotto PostgreSQL

È stata rilasciata la versione 3.35 di MyJSQLView. Per informazioni e download:

È stata rilasciata la versione 1.5.2 di pgbouncer, un “connection pooler” leggero per PostgreSQL. Per informazioni:

Notizie locali su PostgreSQL

Il PGDay francese si terrà a Lione in 7 giugno 2012. Per informazioni:

La conferenza cinese su PostgreSQL si terrà dal 14 al 17 giugno 2012, a Pechino. Per informazioni:

“PostgreSQL Session” si terrà il 4 ottobre 2012 a Parigi, in Francia. Per informazioni:

La conferenza europea di PostgreSQL (PostgreSQL Conference Europe 2012) si terrà a Praga, in Repubblica Ceca, dal 23 al 26 ottobre 2012. La “call for sponsor” è aperta. Per informazioni:

La conferenza PostgreSQL Day Argentina si terrà il 13 novembre 2012 a Bernal (Buenos Aires), presso l’Università Nazionale di Quilmes. La conferenza coprirà argomenti adatti ad utenti, sviluppatori e collaboratori PostgreSQL, così come chi deve prendere decisioni e chi gestisce le politiche. Per maggiori informazioni sulla conferenza, si veda

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Planet PostgreSQL:

Questo notiziario settimanale PostgreSQL è stato realizzato da David Fetter; traduzione parziale in lingua italiana a cura di Carlo Ascani.

 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; per le lingue inglese o tedesca, si scriva rispettivamente a o a Per lo spagnolo a

Patch applicate

Peter Eisentraut pushed:

– libpq: URI parsing fixes. Drop special handling of host component
with slashes to mean Unix-domain socket. Specify it as separate
parameter or using percent-encoding now. Allow omitting username,
password, and port even if the corresponding designators are present
in URI. Handle percent-encoding in query parameter keywords. Alex
Shulgin some documentation improvements by myself

– Translation updates.

Tom Lane pushed:

– Eliminate some more O(N^2) behaviors in pg_dump/pg_restore. This
patch fixes three places (which AFAICT is all of them) where runtime
was O(N^2) in the number of TOC entries, by using an index array to
replace linear searches of the TOC list. This performance issue is
a bit less bad than those recently fixed, because it depends on the
number of items dumped not the number in the source database, so the
problem can be dodged by doing partial dumps. The previous coding
already had an instance of one of the two index arrays needed, but
it was only calculated in parallel-restore cases; now we need it all
the time. I also chose to move the arrays into the ArchiveHandle
data structure, to make this code a bit more ready for the day that
we try to sling multiple ArchiveHandles around in pg_dump or
pg_restore. Since we still need some server-side work before
pg_dump can really cope nicely with tens of thousands of tables,
there’s probably little point in back-patching.

– Teach AbortOutOfAnyTransaction to clean up partially-started
transactions. AbortOutOfAnyTransaction failed to do anything if the
state it saw on entry corresponded to failing partway through
StartTransaction. I fixed AbortCurrentTransaction to cope with that
case way back in commit 60b2444cc3ba037630c9b940c3c9ef01b954b87b,
but evidently overlooked that AbortOutOfAnyTransaction should do
likewise. Back-patch to all supported branches. It’s not clear
that this omission has any more-than-cosmetic consequences, but it’s
also not clear that it doesn’t, so back-patching seems the least
risky choice.

– Rewrite –section option to decouple it from
–schema-only/–data-only. The initial implementation of pg_dump’s
–section option supposed that the existing –schema-only and
–data-only options could be made equivalent to –section settings.
This is wrong, though, due to dubious but long since set-in-stone
decisions about where to dump SEQUENCE SET items, as seen in bug
report from Martin Pitt. (And I’m not totally convinced there
weren’t other bugs, either.) Undo that coupling and instead drive
–section filtering off current-section state tracked as we scan
through the TOC list to call _tocEntryRequired(). To make sure
those decisions don’t shift around and hopefully save a few cycles,
run _tocEntryRequired() only once per TOC entry and save the result
in a new TOC field. This required minor rejiggering of ACL handling
but also allows a far cleaner implementation of
inhibit_data_for_failed_table. Also, to ensure that pg_dump and
pg_restore have the same behavior with respect to the –section
switches, add _tocEntryRequired() filtering to WriteToc() and
WriteDataChunks(), rather than trying to implement section filtering
in an entirely orthogonal way in dumpDumpableObject(). This
required adjusting the handling of the special ENCODING and
STDSTRINGS items, but they were pretty weird before anyway. Minor
other code review for the patch, too.

– Fix incorrect password transformation in contrib/pgcrypto’s DES
crypt(). Overly tight coding caused the password transformation
loop to stop examining input once it had processed a byte equal to
0x80. Thus, if the given password string contained such a byte
(which is possible though not highly likely in UTF8, and perhaps
also in other non-ASCII encodings), all subsequent characters would
not contribute to the hash, making the password much weaker than it
appears on the surface. This would only affect cases where
applications used DES crypt() to encode passwords before storing
them in the database. If a weak password has been created in this
fashion, the hash will stop matching after this update has been
applied, so it will be easy to tell if any passwords were
unexpectedly weak. Changing to a different password would be a good
idea in such a case. (Since DES has been considered inadequately
secure for some time, changing to a different encryption algorithm
can also be recommended.) This code, and the bug, are shared with at
least PHP, FreeBSD, and OpenBSD. Since the other projects have
already published their fixes, there is no point in trying to keep
this commit private. This bug has been assigned CVE-2012-2143, and
credit for its discovery goes to Rubin Xu and Joseph Bonneau.

– Expand the allowed range of timezone offsets to +/-15:59:59 from
Greenwich. We used to only allow offsets less than +/-13 hours,
then it was +/14, then it was +/-15. That’s still not good enough
though, as per today’s bug report from Patric Bechtel. This time I
actually looked through the Olson timezone database to find the
largest offsets used anywhere. The winners are Asia/Manila, at
-15:56:00 until 1844, and America/Metlakatla, at +15:13:42 until
1867. So we’d better allow offsets less than +/-16 hours. Given
the history, we are way overdue to have some greppable #define
symbols controlling this, so make some … and also remove an
obsolete comment that didn’t get fixed the last time. Back-patch to
all supported branches.

– Ignore SECURITY DEFINER and SET attributes for a PL’s call handler.
It’s not very sensible to set such attributes on a handler function;
but if one were to do so, fmgr.c went into infinite recursion
because it would call fmgr_security_definer instead of the handler
function proper. There is no way for fmgr_security_definer to know
that it ought to call the handler and not the original function
referenced by the FmgrInfo’s fn_oid, so it tries to do the latter,
causing the whole process to start over again. Ordinarily such
misconfiguration of a procedural language’s handler could be written
off as superuser error. However, because we allow non-superuser
database owners to create procedural languages and the handler for
such a language becomes owned by the database owner, it is possible
for a database owner to crash the backend, which ideally shouldn’t
be possible without superuser privileges. In 9.2 and up we will
adjust things so that the handler functions are always owned by
superusers, but in existing branches this is a minor security fix.
Problem noted by Noah Misch (after several of us had failed to
detect it :-(). This is CVE-2012-2655.

– Force PL and range-type support functions to be owned by a
superuser. We allow non-superusers to create procedural languages
(with restrictions) and range datatypes. Previously, the
automatically-created support functions for these objects ended up
owned by the creating user. This represents a rather considerable
security hazard, because the owning user might be able to alter a
support function’s definition in such a way as to crash the server,
inject trojan-horse SQL code, or even execute arbitrary C code
directly. It appears that right now the only actually exploitable
problem is the infinite-recursion bug fixed in the previous patch
for CVE-2012-2655. However, it’s not hard to imagine that future
additions of more ALTER FUNCTION capability might unintentionally
open up new hazards. To forestall future problems, cause these
support functions to be owned by the bootstrap superuser, not the
user creating the parent object.

– Update time zone data files to tzdata release 2012c. DST law
changes in Antarctica, Armenia, Chile, Cuba, Falkland Islands, Gaza,
Haiti, Hebron, Morocco, Syria, Tokelau Islands. Historical
corrections for Canada.

– Revert back-branch changes in behavior of age(xid). Per discussion,
it does not seem like a good idea to change the behavior of age(xid)
in a minor release, even though the old definition causes the
function to fail on hot standby slaves. Therefore, revert commit
5829387381d2e4edf84652bb5a712f6185860670 and follow-on commits in
the back branches only.

– Improve comment for GetStableLatestTransactionId().

– Update release notes for 9.1.4, 9.0.8, 8.4.12, 8.3.19.

– Stamp 9.2beta2, 9.1.4, 8.4.12, 9.0.8, 8.3.19.

– Fix memory leaks in failure paths in buildACLCommands and
parseAclItem. This is currently only cosmetic, since all the call
sites just curl up and die in event of a failure return. It might
be important for some future use-case, though, and in any case it
quiets warnings from the clang static analyzer (as reported by Anna
Zaks). Josh Kupershmidt

Heikki Linnakangas pushed:

– Fix integer overflow bug in GiST buffering build calculations. The
result of (maintenance_work_mem * 1024) / BLCKSZ doesn’t fit in a
signed 32-bit integer, if maintenance_work_mem >= 2GB. Use double
instead. And while we’re at it, write the calculations in an easier
to understand form, with the intermediary steps written out and

– Change the way parent pages are tracked during buffered GiST build.
We used to mimic the way a stack is constructed when descending the
tree during normal GiST inserts, but that was quite complicated
during a buffered build. It was also wrong: in GiST, the
left-to-right relationships on different levels might not match each
other, so that when you know the parent of a child page, you won’t
necessarily find the parent of the page to the right of the child
page by following the rightlinks at the parent level. This
sometimes led to “could not re-find parent” errors while building a
GiST index. We now use a simple hash table to track the parent of
every internal page. Whenever a page is split, and downlinks are
moved from one page to another, we update the hash table
accordingly. This is also better for performance than the old
method, as we never need to move right to re-find the parent page,
which could take a significant amount of time for buffers that were
created much earlier in the index build.

– Delete the temporary file used in buffered GiST build, after the
build. There were two bugs here: We forgot to call
gistFreeBuildBuffers() function at the end of build, and we passed
interXact == true to BufFileCreateTemp, so the file wasn’t
automatically cleaned up at end-of-transaction either.

Robert Haas pushed:

– Fix two more bugs in fast-path relation locking. First, the
previous code failed to account for the fact that, during Hot
Standby operation, the startup process takes AccessExclusiveLocks on
relations without setting MyDatabaseId. This resulted in fast path
strong lock counts failing to be incremented with the startup
process took locks, which in turn allowed conflicting lock requests
to succeed when they should not have. Report by Erik Rijkers,
diagnosis by Heikki Linnakangas. Second, LockReleaseAll() failed to
honor the allLocks and lockmethodid restrictions with respect to
fast-path locks. It’s not clear to me whether this produces any
user-visible breakage at the moment, but it’s certainly wrong.
Rearrange order of operations in LockReleaseAll to fix. Noted by
Tom Lane.

Simon Riggs pushed:

– Only throw recovery conflicts when InHotStandby. Bug fix to recent
patch to allow Index Only Scans on Hot Standby. Bug report from
Jaime Casanova

– Provide interim statistics while in mid-checkpoint. Re-implements
similar functionality in 9.1 and previously which was removed during
split of checkpointer and bgwriter. Requested/spotted by Magnus

– Checkpointer starts before bgwriter to avoid missing fsync requests.
Noted while testing Hot Standby startup.

– After any checkpoint, close all smgr files handles in bgwriter

– Copy editing of release notes for couple of my items.

– Clarify description of covering indexes in release notes

– Improve description of pg_stat_statements normalisation in release

– Avoid early reuse of btree pages, causing incorrect query results.
When we allowed read-only transactions to skip assigning XIDs we
introduced the possibility that a fully deleted btree page could be
reused. This broke the index link sequence which could then lead to
indexscans silently returning fewer rows than would have been
correct. The actual incidence of silent errors from this is thought
to be very low because of the exact workload required and locking
pre-conditions. Fix is to remove pages only if index page
opaque->btpo.xact precedes RecentGlobalXmin. Noah Misch, reviewed
by Simon Riggs

Bruce Momjian pushed:

– In pg_upgrade, report pre-PG 8.1 plpython helper functions left in
the public schema that no longer point to valid shared object
libraries, and suggest a solution.

Patch rifiutate (per adesso)

Nessuno è stato scontetao questa settimana. :-)

Patch in attesa

Alexander Korotkov sent in a WIP patch to use 2d-mapping-based index

scanning for ranges.

Andres Freund sent in a patch to fix walsender wakeup handling.

Peter Geoghegan sent in a patch to adjust group commit behavior.

Mark Dilger sent in a patch to speed up file access on Windows.

Robert Haas sent in a patch to avoid taking a heavyweight lock on the
metapage of a hash index.

Simon Riggs and Jeff Janes traded patches to increase performance of
dropping large numbers of tables.

Jeff Janes sent in another revision of his patch to add a new
transaction type to pgbench.

Ants Aasma sent in a patch that makes the clock sweep lock-free in the
common case.

Bruce Momjian sent in a patch to pg_upgrade which adds checks to
verify the the old/new servers have the same install-user oid.

Brar Piening sent in a patch to make postgres build with Visual Studio
2012 RC.

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