== WöchentlicherPostgreSQL Newsletter - 22.August 2010

Der Originalartikel befindet sich unter:

http://www.postgresql.org/community/weeklynews/pwn20100822



== Wöchentlicher PostgreSQL Newsletter - 22. August 2010 ==

Der Call for Papers für den PGDay.EU 2010 am 6.-8. Dezember in
Stuttgart ist nun eröffnet.
http://2010.pgday.eu/callforpapers

== PostgreSQL Produkt Neuigkeiten ==

pgpool-II 3.0beta1, ein Connection Pooler und mehr,
ist erschienen.
http://pgfoundry.org/projects/pgpool/

== PostgreSQL Jobs im August ==

http://archives.postgresql.org/pgsql-jobs/2010-08/threads.ph p

== PostgreSQL Lokal ==

Der Call for Papers für West ist bis zum 5. September 2010 offen.
Details unter:
http://www.postgresqlconference.org/

== PostgreSQL in den News ==

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

Dieser wöchentliche PostgreSQL Newsletter wurde erstellt von David
Fetter.

Sende Neuigkeiten und Ankündigungen bis Sonntag, 15 Uhr Pazifischer
Zeit. Bitte sende englische Beiträge an david@fetter.org, deutsche an
pwn@pgug.de, italienische an pwn@itpug.org.

== Angewandte Patches ==

Tom Lane committed:

- In pgsql/src/backend/utils/init/miscinit.c, arrange to fsync the
contents of lockfiles (both postmaster.pid and the socket lockfile)
when writing them. The lack of an fsync here may well explain two
different reports we've seen of corrupted lockfile contents, which
doesn't particularly bother the running server but can prevent a new
server from starting if the old one crashes. Per suggestion from
Alvaro Herrera. Back-patch to all supported versions.

- Add missing handling of PlannedStmt.transientPlan in
copyfuncs/outfuncs. _outPlannedStmt is only debug support, so the
omission there was not very serious, but the omission in
_copyPlannedStmt is a real bug. The consequence would be that a
copied plan tree would never be marked as a transient plan, so that
we would forget we ought to replan it after some not-yet-ready index
becomes ready for use. This might explain some past complaints
about indexes created with CREATE INDEX CONCURRENTLY not being used
right away. Problem spotted by Yeb Havinga. Back-patch to 8.3,
where the field was added.

- Fix failure of "ALTER TABLE t ADD COLUMN c serial" when done by
non-owner. The implicitly created sequence was created as owned by
the current user, who could be different from the table owner, eg if
current user is a superuser or some member of the table's owning
role. This caused sanity checks in the SEQUENCE OWNED BY code to
spit up. Although possibly we don't need those sanity checks, the
safest fix seems to be to make sure the implicit sequence is
assigned the same owner role as the table has. (We still do all
permissions checks as the current user, however.) Per report from
Josh Berkus. Back-patch to 9.0. The bug goes back to the invention
of SEQUENCE OWNED BY in 8.2, but the fix requires an API change for
DefineRelation(), which seems to have potential for breaking
third-party code if done in a minor release. Given the lack of
prior complaints, it's probably not worth fixing in the stable
branches.

- Rename utf2ucs() to utf8_to_unicode(), and export it so it can be
used elsewhere. Similarly rename the version in mbprint.c, not
because this affects anything but just to keep the two copies in
exact sync. There was some discussion of having only one copy in
src/port/ instead, but this function is so small and unlikely to
change that that seems like overkill. Slightly editorialized
version of a patch by Joseph Adams. (The bug-fix aspect of his
patch was applied separately, and back-patched.)

- In pgsql/src/backend/executor/nodeModifyTable.c, reset the
per-output-tuple exprcontext each time through the main loop in
ExecModifyTable(). This avoids memory leakage when trigger
functions leave junk behind in that context (as they more or less
must). Problem and solution identified by Dean Rasheed. I'm a bit
concerned about the longevity of this solution --- once a plan can
have multiple ModifyTable nodes, we are very possibly going to have
to do something different. But it should hold up for 9.0.

- In pgsql/src/backend/commands/trigger.c, fix possible corruption of
AfterTriggerEventLists in subtransaction rollback.
afterTriggerInvokeEvents failed to adjust events->tailfree when
truncating the last chunk of an event list. This could result in
the data being "de-truncated" by afterTriggerRestoreEventList during
a subsequent subtransaction abort. Even that wouldn't kill us,
because the re-added data would just be events marked DONE ---
unless the data had been partially overwritten by new events. Then
we might crash, or in any case misbehave (perhaps fire triggers
twice, or fire triggers with the wrong event data). Per bug #5622
from Thue Janus Kristensen. Back-patch to 8.4 where the current
trigger list representation was introduced.

- In pgsql/src/backend/storage/buffer/localbuf.c, allocate local
buffers in a context of their own, rather than dumping them into
TopMemoryContext. This makes no functional difference, but makes it
easier to see what the space is being used for in MemoryContextStats
dumps. Per a recent example in which I was surprised by the size of
TopMemoryContext.

- In pgsql/src/pl/plpgsql/src/pl_exec.c, be a bit less cavalier with
both the code and the comment for UNKNOWN fix.

- In pgsql/src/pl/plpgsql/src/pl_exec.c, keep exec_simple_check_plan()
from thinking "SELECT foo INTO bar" is simple. It's not clear if
this situation can occur in plpgsql other than via the EXECUTE USING
case Heikki illustrated, which I will shortly close off. However,
ignoring the intoClause if it's there is surely wrong, so let's
patch it for safety. Backpatch to 8.3, which is as far back as this
code has a PlannedStmt to deal with. There might be another way to
make an equivalent test before that, but since this is just
preventing hypothetical bugs, I'm not going to obsess about it.

- In pgsql/src/pl/plpgsql/src/gram.y, allow USING and INTO clauses of
plpgsql's EXECUTE to appear in either order. Aside from being more
forgiving, this prevents a rather surprising misbehavior when the
"wrong" order was used: the old code didn't throw a syntax error,
but absorbed the INTO clause into the last USING expression, which
then did strange things downstream. Intentionally not changing the
documentation; we'll continue to advertise only the "standard"
clause order. Backpatch to 8.4, where the USING clause was added to
EXECUTE.

- Bring some sanity to the trace_recovery_messages code and docs. Per
gripe from Fujii Masao, though this is not exactly his proposed
patch. Categorize as DEVELOPER_OPTIONS and set context PGC_SIGHUP,
as per Fujii, but set the default to LOG because higher values
aren't really sensible (see the code for trace_recovery()). Fix the
documentation to agree with the code and to try to explain what the
variable actually does. Get rid of no-op calls trace_recovery(LOG),
which accomplish nothing except to demonstrate that this option
confuses even its author.

- Avoid saying "random" when randomness is not actually meant. Per
Thom Brown.

- In pgsql/src/backend/parser/gram.y, add missing processing of
OptTemp in CREATE IF NOT EXISTS variant for typed tables. Noted by
Robert Haas.

- In pgsql/src/bin/pg_dump/pg_backup_archiver.c, improve parallel
restore's ability to cope with selective restore (-L option). The
original coding tended to break down in the face of modified restore
orders, as shown in bug #5626 from Albert Ullrich, because it would
flip over into parallel-restore operation too soon. That causes
problems because we don't have sufficient dependency information in
dump archives to allow safe parallel processing of SECTION_PRE_DATA
items. Even if we did, it's probably undesirable to allow that to
override the commanded restore order. To fix the problem of omitted
items causing unexpected changes in restore order, tweak
SortTocFromFile so that omitted items end up at the head of the list
not the tail. This ensures that they'll be examined and their
dependencies will be marked satisfied before we get to any
interesting items. In HEAD and 9.0, we can easily change
restore_toc_entries_parallel so that all SECTION_PRE_DATA items are
guaranteed to be processed in the initial serial-restore loop, and
hence in commanded order. Only DATA and POST_DATA items are
candidates for parallel processing. For them there might be
variations from the commanded order because of parallelism, but we
should do it in a safe order thanks to dependencies. In 8.4 it's
much harder to make such a guarantee. I settled for not letting the
initial loop break out into parallel processing mode if it sees a
DATA/POST_DATA item that's not to be restored; this at least
prevents a non-restorable item from causing premature exit from the
loop. This means that 8.4 will be more likely to fail given a
badly-ordered -L list than 9.x, but we don't really promise any such
thing will work anyway.

- In pgsql/src/backend/utils/adt/arrayfuncs.c, use a
non-locale-dependent definition of isspace() in array_in/array_out.
array_in discards unquoted leading and trailing whitespace in array
values, while array_out is careful to quote array elements that
contain whitespace. This is problematic when the definition of
"whitespace" varies between locales: array_in could drop characters
that were meant to be part of the value. To avoid that, lock down
"whitespace" to mean only the traditional six ASCII space
characters. This change also works around a bug in OS X and some
older BSD systems, in which isspace() could return true for
character fragments in UTF8 locales. (There may be other places in
PG where that bug could cause problems, but this is the only one
complained of so far; see recent report from Steven Schlansker.)
Back-patch to 9.0, but not further. Given the lack of previous
reports of trouble, changing this behavior in stable branches seems
to offer more risk of breaking applications than reward of avoiding
problems.

Peter Eisentraut committed:

- Spell and markup checking for docs.

- In pgsql/doc/src/sgml/lo.sgml, revert: looks like Binary Large
OBject[sic] wasn't a misspelling

- Backpatch some blatant spelling mistakes in the docs.

- Remove extra newlines at end and beginning of files, add missing
newlines at end of files.

Michael Meskes committed:

- Applied Zoltan Boszormenyi's patch to fix a few memleaks in ecpg's
pgtypeslib.

Heikki Linnakangas committed:

- In pgsql/src/backend/parser/parse_param.c, coerce 'unknown' type
parameters to the right type in the fixed-params parse_analyze()
function. That case occurs e.g with PL/pgSQL EXECUTE ... USING
'stringconstant'. The coercion with a CoerceViaIO node. The result
is similar to the coercion via input function performed for unknown
constants in coerce_type(), except that this happens at runtime.
Backpatch to 9.0. The issue is present in 8.4 as well, but the
coerce param hook infrastructure this patch relies on was introduced
in 9.0. Given the lack of user reports and harmlessness of the bug,
it's not worth attempting a different fix just for 8.4.

- Revert patch to coerce 'unknown' type parameters in the backend. As
Tom Lane pointed out, it would need a 2nd pass after the whole query
is processed to correctly check that an unknown Param is coerced to
the same target type everywhere. Adding the 2nd pass would add a
lot more code, which doesn't seem worth the risk given that there
isn't much of a use case for passing unknown Params in the first
place. The code would work without that check, but it might be
confusing and the behavior would be different from the varparams
case. Instead, just coerce all unknown params in a PL/pgSQL USING
clause to text. That's simple, and is usually what users expect.
Revert the patch in CVS HEAD and master, and backpatch the new
solution to 8.4. Unlike the previous solution, this applies easily
to 8.4 too.

Robert Haas committed:

- Tidy up a few calls to smrgextend(). In the new API introduced by
my patch to include the backend ID in temprel filenames, the last
argument to smrgextend() became skipFsync rather than isTemp, but
these calls didn't get the memo. It's not really a problem to pass
rel->rd_istemp rather than just plain false, because smgrextend()
now automatically skips the fsync for temprels anyway, but this
seems cleaner and saves some minute number of cycles.

- In pgsql/src/backend/storage/buffer/bufmgr.c, remove the isLocalBuf
argument from ReadBuffer_common. Since an SMgrRelation now knows
whether or not the underlying relation is temporary, there's no
point in also passing that information via an additional argument.

Magnus Hagander committed:

- Add vacuum and analyze counters to pg_stat_*_tables views.

- In pgsql/src/test/regress/expected/rules.out, adjust regression
tests for previous commit, that I forgot to include...

Bruce Momjian committed:

- In pgsql/doc/src/sgml/config.sgml, document that
autovacuum_freeze_max_age is used for pg_clog recycling. We already
mentioned xid wraparound.

== Abgelehnte Patches (bis jetzt) ==

No one was disappointed this week :-)

== Eingesandte Patches ==

Pavel Stehule sent in two revisions of a patch to extend psql's tab
completion to more entities.

KaiGai Kohei sent in a patch to implement preload libraries for
single-user mode.

Peter Eisentraut sent in a prototype query progress indicator.

Quan Zongliang sent in a patch to enable pg_ctl on Windows to select a
service start type (auto or on-demand), then a follow-up patch to add
the docs. David Fetter unified these into standard format.

Robert Haas and Alex Hunsaker traded patches to create a new tool for
git histories.

Peter Eisentraut sent in a patch to fix an issue in PL/PythonU with
Python 2.7.

Heikki Linnakangas sent in a WIP patch to fix an issue with type
coercion in PL/pgsql's EXECUTE ... USING construct.

Pavel Stehule sent in two revisions of a patch to add MEDIAN() and
PERCENTILE() as contrib modules.

Boxuan Zhai sent in another revision of the MERGE patch.

Robert Haas sent in another refactor of comment.c.

Martin Pitt sent in a patch to add a system-wide fallback directory
for SSL root certificates.

KaiGai Kohei sent in a patch to add a security hook at authorization
time.

Robert Haas sent in a patch to clean up smgr, which kicked off a
discussion of the design of the abstraction layers nearby.

Magnus Hagander sent in a patch to add columns the pg_stat_*_tables
which record the number of [auto]vacuum and [auto]analyze runs.

Peter Eisentraut sent in a patch to refactor makeVar in the back end.

Erik Rijkers sent in two revisions of a patch to make the debug
messages in pg_archivecleanup more consistent.

Magnus Hagander sent in a patch to track more vacuum stats.

--
Andreas 'ads' Scherbaum
Deutsche PostgreSQL User Group: http://www.pgug.de/
DPWN: http://andreas.scherbaum.la/blog/categories/18-PWN

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