== PostgreSQL Weekly News - September 09 2007 == - Mailing list pgsql-announce

== PostgreSQL Weekly News - September 09 2007 ==

== PostgreSQL Product News ==

Another PostgreSQL Diff Tool 1.0.0_beta26 released.
http://pgfoundry.org/projects/apgdiff/

PSQL-Query 0.01 released.
http://search.cpan.org/~ecarroll/PSQL-Query-0.01_01/bin/psql-plus

OpenMFG 2.2 and PostBooks 2.2 released.
http://www.xtuple.com/

== PostgreSQL Jobs for September ==

http://archives.postgresql.org/pgsql-jobs/2007-09/threads.php

== PostgreSQL Local ==

PostgreSQL Fall Conference will be October 20, 2007 in Portland.
http://www.postgresqlconference.org/

There will be a PostgreSQL booth at Ohio Linuxfest on September 29th,
and Robert Treat will be speaking.
http://www.ohiolinux.org/speakers.html#talk1_06

SFPUG presents Fred Moyer on Big Blue Ball of Mud, September 11, 7:30pm
http://postgresql.meetup.com/1/calendar/6143101/

== PostgreSQL in the News ==

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

General Bits, Archives and occasional new articles:
http://www.varlena.com/GeneralBits/

PostgreSQL Weekly News is brought to you this week by David Fetter

Submit news and announcements by Sunday at 3:00pm Pacific time.
Please send English language ones to david@fetter.org, German to
pwn@pgug.de.

== Applied Patches ==

Teodor Sigaev committed:

- Improve page split in rtree emulation.  Now when a split result has
  a big misalignement, it tries to split page basing on distribution
  of box's centers.  Per report from Tom Dolafi.

- Fix infinite loop in rank_cd for some corner queries.  Per Daniele
  Varrazzo.

- Improvements from  Heikki Linnakangas.

- Improve various checks by Heikki Linnakangas.

- Refactor of tsearch code by Heikki Linnakangas with small
  editorization by me.

- Add turkish stopword list.  Thanks to Devrim GUNDUZ.

Bruce Momjian committed:

- Add Hash thread URL to TODO:
  "http://archives.postgresql.org/pgsql-hackers/2007-09/msg00051.php"

- Mark TODO as DONE: "Reduce XID consumption of read-only queries."

Andrew Dunstan committed:

- Fix typo in regression Makefile.

- Provide for a file specifying non-standard config options for temp
  install for pg_regress, via --temp-config option. Pick this up in
  the make file via TEMP_CONFIG setting.

- Provide for binary input/output of enums, to fix complaint from
  Merlin Moncure.  This just provides text values, we're not exposing
  the underlying Oid representation.  Catalog version bumped.

Michael Meskes committed:

- In pgsql/src/interfaces/ecpg, synced parser and keyword list.

Tom Lane committed:

- Set the correct context (PGC_SIGHUP) for log_autovacuum, per ITAGAKI
  Takahiro.  Fix grammatical errors in its description.

- Code review for GUC revert-values-if-removed-from-postgresql.conf
  patch; and in passing, fix some bogosities dating from the
  custom_variable_classes patch.  Fix guc-file.l to correctly check
  changes in custom_variable_classes that are attempted concurrently
  with additions/removals of custom variables, and don't allow the new
  setting to be applied in advance of checking it.  Clean up messy and
  undocumented situation for string variables with NULL boot_val.  Fix
  DefineCustomVariable functions to initialize boot_val correctly.
  Prevent find_option from inserting bogus placeholders for custom
  variables that are simply inquired about rather than being set.

- Replace the former method of determining snapshot xmax --- to wit,
  calling ReadNewTransactionId from GetSnapshotData --- with a
  "latestCompletedXid" variable that is updated during transaction
  commit or abort.  Since latestCompletedXid is written only in places
  that had to lock ProcArrayLock exclusively anyway, and is read only
  in places that had to lock ProcArrayLock shared anyway, it adds no
  new locking requirements to the system despite being cluster-wide.
  Moreover, removing ReadNewTransactionId from snapshot acquisition
  eliminates the need to take both XidGenLock and ProcArrayLock at the
  same time.  Since XidGenLock is sometimes held across I/O this can
  be a significant win.  Some preliminary benchmarking suggested that
  this patch has no effect on average throughput but can significantly
  improve the worst-case transaction times seen in pgbench.  Concept
  by Florian Pflug, implementation by Tom Lane.

- Don't take ProcArrayLock while exiting a transaction that has no
  XID; there is no need for serialization against snapshot-taking
  because the xact doesn't affect anyone else's snapshot anyway.  Per
  discussion.  Also, move various info about the interlocking of
  transactions and snapshots out of code comments and into a
  hopefully-more-cohesive discussion in access/transam/README.  Also,
  remove a couple of now-obsolete comments about having to force some
  WAL to be written to persuade RecordTransactionCommit to do its
  thing.

- Allow CREATE INDEX CONCURRENTLY to disregard transactions in other
  databases, per gripe from hubert depesz lubaczewski.  Patch from
  Simon Riggs.

- Make eval_const_expressions() preserve typmod when simplifying
  something like null::char(3) to a simple Const node.  (It already
  worked for non-null values, but not when we skipped evaluation of a
  strict coercion function.) This prevents loss of typmod knowledge in
  situations such as exhibited in bug #3598.  Unfortunately there
  seems no good way to fix that bug in 8.1 and 8.2, because they
  simply don't carry a typmod for a plain Const node.  In passing I
  made all the other callers of makeNullConst supply "real" typmod
  values too, though I think it probably doesn't matter anywhere else.

- Volatile-qualify the ProcArray PGPROC pointer in a bunch of routines
  that examine fields that could change under them.  This is just to
  make really sure that when we are fetching a value 'only once',
  that's what actually happens.  Possibly this is a bug that should be
  back-patched, but in the absence of solid evidence that it's needed,
  I won't bother.

- Quick hack to make the VXID of a prepared transaction be -1/XID, so
  that different prepared xacts can be told apart in the pg_locks
  view.  Per suggestion from Florian.

- Implement lazy XID allocation: transactions that do not modify any
  database rows will normally never obtain an XID at all.  We already
  did things this way for subtransactions, but this patch extends the
  concept to top-level transactions.  In applications where there are
  lots of short read-only transactions, this should improve
  performance noticeably; not so much from removal of the actual
  XID-assignments, as from reduction of overhead that's driven by the
  rate of XID consumption.  We add a concept of a "virtual transaction
  ID" so that active transactions can be uniquely identified even if
  they don't have a regular XID.  This is a much lighter-weight
  concept: uniqueness of VXIDs is only guaranteed over the short term,
  and no on-disk record is made about them.  Florian Pflug, with some
  editorialization by Tom.

- In pgsql/doc/src/sgml/textsearch.sgml, sync examples of psql \dF
  output with current CVS HEAD behavior.  Random other wordsmithing.

- Support SET FROM CURRENT in CREATE/ALTER FUNCTION, ALTER DATABASE,
  ALTER ROLE.  (Actually, it works as a plain statement too, but I
  didn't document that because it seems a bit useless.)  Unify
  VariableResetStmt with VariableSetStmt, and clean up some ancient
  cruft in the representation of same.

== Rejected Patches (for now) ==

No one was disappointed this week :-)

== Pending Patches ==

Heikki Linnakangas sent in a document update to version 14 of the HOT
patch.

Heikki Linnakangas sent in a refactor for the tsearch2 code.

Pavan Deolasee sent in version 15 of the HOT patch.

Andrew Dunstan sent in a patch which adds temp_config configuration.

Greg Smith sent in a patch which does just-in-time background
writing.

Tom Lane sent in a WIP patch for latestCompletedXid method of
computing snapshot xmax.

Andrew Dunstan sent in a WIP patch to replace MSVC build scripts
build.bat and vcregress.bat with build.pl and vcregress.pl
respectively.

Sibte Abbas sent in a patch which implements the \# TODO for psql.