PostgreSQL Weekly News – April 25 2010
== PostgreSQL Weekly News – April 25 2010 ==
SEAPUG and PDXPUG will be staffing a booth at LFNW – stop by!
Simon Riggs and Hannu Krosing will be speaking about PostgreSQL at
“Pycon Italia 4” (the Italian Python conference) in Florence, Italy,
on May 8 and 9, 2010.
Registration for PGCon 2010 is open. Rooms fill up fast, so if you’re
going, act soon.
== PostgreSQL Product News ==
PostgreSQL Maestro 10.4, a GUI for PostgreSQL administration
development on Windows, released.
DBD::Pg 2.17.0, a Perl connector for PostgreSQL, released.
pgpool-II 2.3.3, a connection pooler and more, released.
piggly 1.2.0, a PL/pgsql code coverage tool, released.
== PostgreSQL 9.0 Feature of the Week ==
Functions can now have default values for parameters.
== PostgreSQL Jobs for April ==
== PostgreSQL Local ==
The CfP is open for CHAR(10) in Oxford, England on July 1-3 2010.
Proposals are due April 20.
Bruce Momjian will be speaking about PostgreSQL Replication Solutions
at the NYPUG meeting on April 20th at 6:30-8:30pm at Penn Plaza.
Details and RSVP below.
Linuxfest Northwest 2010 will take place in Bellingham, Washington,
USA on April 24 and 25. Session, Booth and Sponsorship are available.
Andreas (ads) Scherbaum will be teaching a “PostgreSQL for Corporate
Use” course at the adult education center in Magdeburg, Germany May
3-7, 2010. Details below:
PgCon 2010 will be held May 20-21 2010 in Ottawa with tutorials before
on the 18th and 19th.
The CfP for OSBridge is open! OSBridge will be June 1-4, 2010 in
Michael Renner will be speaking at AMOOCON, which goes from June 4-6, 2010.
Southeast Linuxfest 2010 will take place in Spartanburg, SC, USA on
June 12-13. Booths and sponsorships are still available.
OSCON will take place in Portland, Oregon July 19-23, 2010.
== PostgreSQL in the News ==
Planet PostgreSQL: http://planet.postgresql.org/
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== Applied Patches ==
Magnus Hagander committed:
– Add wrapper function libpqrcv_PQexec() in the walreceiver that uses
async libpq to send queries, making the waiting for responses
interruptible on platforms where PQexec() can’t normally be
interrupted by signals, such as win32. Fujii Masao and Magnus
Tom Lane committed:
– In pgsql/src/backend/access/nbtree/nbtxlog.c, fix uninitialized
local variables. Not sure why gcc doesn’t complain about these —
maybe because they’re effectively unused? MSVC does complain
though, per buildfarm.
– Move the responsibility for calling StartupXLOG into InitPostgres,
for those process types that go through InitPostgres; in particular,
bootstrap and standalone-backend cases. This ensures that we have
set up a PGPROC and done some other basic initialization steps
(corresponding to the if (IsUnderPostmaster) block in
AuxiliaryProcessMain) before we attempt to run WAL recovery in a
standalone backend. As was discovered last September, this is
necessary for some corner-case code paths during WAL recovery,
particularly end-of-WAL cleanup. Moving the bootstrap case here too
is not necessary for correctness, but it seems like a good idea
since it reduces the number of distinct code paths.
– In pgsql/src/backend/replication/walreceiver.c, fix code that
doesn’t work on machines with strict alignment requirements: must
use memcpy here rather than struct assignment. In passing,
rearrange some randomly-ordered declarations to be a tad less
– Arrange for client authentication to occur before we select a
specific database to connect to. This is necessary for the walsender
code to work properly (it was previously using an untenable
assumption that template1 would always be available to connect to).
This also gets rid of a small security shortcoming that was
introduced in the original patch to eliminate the flat
authentication files: before, you could find out whether or not the
requested database existed even if you couldn’t pass the
authentication checks. The changes needed to support this are
mainly just to treat pg_authid and pg_auth_members as nailed
relations, so that we can read them without having to be able to
locate real pg_class entries for them. This mechanism was already
debugged for pg_database, but we hadn’t recognized the value of
applying it to those catalogs too. Since the current code doesn’t
have support for accessing toast tables before we’ve brought up all
of the relcache, remove pg_authid’s toast table to ensure that no
one can store an out-of-line toasted value of rolpassword. The case
seems quite unlikely to occur in practice, and was effectively
unsupported anyway in the old “flatfiles” implementation. Update
genbki.pl to actually implement the same rules as bootstrap.c does
for not-nullability of catalog columns. The previous coding was a
bit cheesy but worked all right for the previous set of bootstrap
catalogs. It does not work for pg_authid, where rolvaliduntil needs
to be nullable. Initdb forced due to minor catalog changes (mainly
the toast table removal).
– Move the check for whether walreceiver has authenticated as a
superuser from walsender.c, where it didn’t really belong, to
postinit.c where it does belong (and is essentially free, too).
– Fix pg_hba.conf matching so that replication connections only match
records with database = replication. The previous coding would
allow them to match ordinary records too, but that seems like a
recipe for security breaches. Improve the messages associated with
no-such-pg_hba.conf entry to report replication connections as such,
since that’s now a critical aspect of whether the connection
matches. Make some cursory improvements in the related
– Enforce superuser permissions checks during ALTER ROLE/DATABASE SET,
rather than during define_custom_variable(). This entails rejecting
an ALTER command if the target variable doesn’t have a known
(non-placeholder) definition, unless the calling user is superuser.
When the variable *is* known, we can correctly apply the rule that
only superusers can issue ALTER for SUSET parameters. This allows
define_custom_variable to apply ALTER’s values for SUSET parameters
at module load time, secure in the knowledge that only a superuser
could have set the ALTER value. This change fixes a longstanding
gotcha in the usage of SUSET-level custom parameters; which is a
good thing to fix now that plpgsql defines such a parameter.
Simon Riggs committed:
– In pgsql/src/backend/storage/ipc/procarray.c, check
RecoveryInProgress() while holding ProcArrayLock during snapshots.
This prevents a rare, yet possible race condition at the exact
moment of transition from recovery to normal running.
– Add new message for explicit rejection by pg_hba.conf. Implicit
rejection retains same message as before.
– Fix oversight in collecting values for cleanup_info records.
vacuum_log_cleanup_info() now generates log records with a valid
latestRemovedXid set in all cases. Also be careful not to zero the
value when we do a round of vacuuming part-way through
lazy_scan_heap(). Incidentally, this reduces frequency of conflicts
in Hot Standby.
– Relax locking during GetCurrentVirtualXIDs(). Earlier improvements
to handling of btree delete records mean that all snapshot conflicts
on standby now have a valid, useful latestRemovedXid. Our earlier
approach using LW_EXCLUSIVE was useful when we didnt always have a
valid value, though is no longer useful or necessary. Asserts added
to code path to prove and ensure this is the case. This will reduce
contention and improve performance of larger Hot Standby servers.
– In pgsql/src/backend/commands/vacuumlazy.c, only send cleanup_info
messages if VACUUM removes any tuples. There is no other purpose
for this message type than to report the latestRemovedXid of removed
tuples, prior to index scans. Removes overlooked path for sending
invalid latestRemovedXid. Fixes buildfarm failure on centaur.
– Further reductions in Hot Standby conflict processing. These come
from the realistion that HEAP2_CLEAN records don’t always remove
user visible data, so conflict processing for them can be skipped.
Confirm validity using Assert checks, clarify circumstances under
which we log heap_cleanup_info records. Tuning arises from bug
fixing of earlier safety check failures.
– Optimise btree delete processing when no active backends. Clarify
comments, downgrade a message to DEBUG and remove some debug
counters. Direct from ideas by Heikki Linnakangas.
– Make CheckRequiredParameterValues() depend upon correct combination
of parameters. Fix bug report by Robert Haas that error message and
hint was incorrect if wrong mode parameters specified on master.
Internal changes only. Proposals for parameter simplification on
master/primary still under way.
– Previous patch revoked following objections.
– Add missing optimizer hooks for function cost and number of rows.
Closely follow design of other optimizer hooks: if hook exists
retrieve value from plugin; if still not set then get from cache.
– Patch revoked because of objections.
Robert Haas committed:
– Update docs as to when WAL logging can be skipped. In 8.4 and
prior, WAL-logging could potentially be skipped whenever
archive_mode=off. With streaming replication, this is now true only
if max_wal_senders=0. Fujii Masao, with light copyediting by me.
– Rename standby_keep_segments to wal_keep_segments. Also, make the
name of the GUC and the name of the backing variable match. Alnong
the way, clean up a couple of slight typographical errors in the
– Fix various instances of “the the”. Two of these were pointed out
by Erik Rijkers; the rest I found.
ITAGAKI Takahiro committed:
– In pgsql/src/backend/utils/adt/pg_locale.c, fix encoding issue when
lc_monetary or lc_numeric are different encoding from lc_ctype, that
could happen on Windows. We need to change lc_ctype together with
lc_monetary or lc_numeric, and convert strings in lconv from
lc_ctype encoding to the database encoding. The bug reported by
Mikko, original patch by Hiroshi Inoue, with changes by Bruce and
Peter Eisentraut committed:
– In pgsql/src/backend/utils/misc/guc.c, fix message punctuation.
Bruce Momjian committed:
– In pgsql/src/backend/utils/adt/pg_locale.c, add C comments for
recent to_char(‘L’) fix for Win32.
== Rejected Patches (for now) ==
Simon Riggs’s patch to speed up ALTER TABLE…SET TABLESPACE. Timing
is not right for 9.0.
Nikhil Sontakke’s patch to estimate the costs of SRFs.
Simon Riggs’s patch to make the “ALL” in GRANT … ON ALL optional.
== Pending Patches ==
Robert Haas sent in a patch to cause walsender not to consume
Simon Riggs sent in a patch to implement prefetching during replay of
btree delete records. The patch is intended to fix a performance
issue reported by Erik Rijkers where a Hot Standby slave’s performance
is much lower than on the master’s.
Bruce Momjian sent in a patch per prior discussion to re-order the
timestamps displayed in the pg_stat_activity view.
Robert Haas sent in a WIP patch to ush isTemp down into the smgr
layer. This is intended to be infrastructure for global temporary
tables per the SQL standard.
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