Waiting for 9.0 – table and index sizes

On 19th of January Tom Lane committed really brilliant patch:

Log Message:
-----------
Add pg_table_size() and pg_indexes_size() to provide more user-friendly
wrappers around the pg_relation_size() function.
 
Bernd Helmle, reviewed by Greg Smith

Continue reading Waiting for 9.0 – table and index sizes

Waiting for 9.0 – Streaming replication

The BIG feature. The feature that made PostgreSQL leap from 8.4 to 9.0. Patch was written by Fujii Masao, and committed by Heikki Linnakangas on 15th of January 2010:

Log Message:
-----------
Introduce Streaming Replication.
 
This includes two new kinds of postmaster processes, walsenders and
walreceiver. Walreceiver is responsible for connecting to the primary server
and streaming WAL to disk, while walsender runs in the primary server and
streams WAL from disk to the client.
 
Documentation still needs work, but the basics are there. We will probably
pull the replication section to a new chapter later on, as well as the
sections describing file-based replication. But let's do that as a separate
patch, so that it's easier to see what has been added/changed. This patch
also adds a new section to the chapter about FE/BE protocol, documenting the
protocol used by walsender/walreceivxer.
 
Bump catalog version because of two new functions,
pg_last_xlog_receive_location() and pg_last_xlog_replay_location(), for
monitoring the progress of replication.
 
Fujii Masao, with additional hacking by me

Continue reading Waiting for 9.0 – Streaming replication

Waiting for 8.5 – VACUUM FULL change

Some time ago Josh Berkus wrote about possible changes in VACUUM FULL.

Now these changes came to life. By now, I mean 6th of January, when Takahiro Itagaki committed his patch:

Log Message:
-----------
Support rewritten-based full vacuum as VACUUM FULL. Traditional
VACUUM FULL was renamed to VACUUM FULL INPLACE. Also added a new
option -i, --inplace for vacuumdb to perform FULL INPLACE vacuuming.
 
Since the new VACUUM FULL uses CLUSTER infrastructure, we cannot
use it for system tables. VACUUM FULL for system tables always
fall back into VACUUM FULL INPLACE silently.
 
Itagaki Takahiro, reviewed by Jeff Davis and Simon Riggs.

Continue reading Waiting for 8.5 – VACUUM FULL change

Waiting for 8.5 – Hot Standby

On 19th of December Simon Riggs committed a patch that will quite likely be the single most-talked-about change in PostgreSQL 8.5:

Log Message:
-----------
Allow read only connections during recovery, known as Hot Standby. 
 
Enabled by recovery_connections = on (default) and forcing archive recovery
using a recovery.conf. Recovery processing now emulates the original
transactions as they are replayed, providing full locking and MVCC behaviour
for read only queries. Recovery must enter consistent state before
connections are allowed, so there is a delay, typically short, before
connections succeed. Replay of recovering transactions can conflict and in
some cases deadlock with queries during recovery; these result in query
cancellation after max_standby_delay seconds have expired. Infrastructure
changes have minor effects on normal running, though introduce four new
types of WAL record. 
 
New test mode "make standbycheck" allows regression tests of
static command behaviour on a standby server while in recovery. Typical and
extreme dynamic behaviours have been checked via code inspection and manual
testing. Few port specific behaviours have been utilised, though primary
testing has been on Linux only so far. 
 
This commit is the basic patch. Additional changes will follow in this
release to enhance some aspects of behaviour, notably improved handling of
conflicts, deadlock detection and query cancellation. Changes to VACUUM FULL
are also required.
 
Simon Riggs, with significant and lengthy review by Heikki Linnakangas,
including streamlined redesign of snapshot creation and two-phase commit.
 
Important contributions from Florian Pflug, Mark Kirkwood, Merlin Moncure,
Greg Stark, Gianni Ciolli, Gabriele Bartolini, Hannu Krosing, Robert Haas,
Tatsuo Ishii, Hiroyuki Yamada plus support and feedback from many other
community members.

Continue reading Waiting for 8.5 – Hot Standby

Waiting for 8.5 – PL/pgSQL by default

On 18th of December Bruce Momjian committed very important, but relatively small, patch:

Log Message:
-----------
Install server-side language PL/pgSQL by default.

There is no point in showing it, commit log tells all – basically from 8.5 on PL/pgSQL will be enabled by default in all databases.

There was time when people rejected “stored procedure" suggestions, because they didn't have any PL/, and installing them required superuser privileges. For some time (since 8.3) you no longer need to be superuser to create trusted languages, so the problem mostly vanished, but now, it will simply cease to exist 🙂

Waiting for 8.5 – ordered aggregates

On 15th of December Tom Lane committed patch by Andrew Gierth (aka RhodiumToad), which adds interesting capability:

Log Message:
-----------
Support ORDER BY within aggregate function calls, at long last providing a
non-kluge method for controlling the order in which values are fed to an
aggregate function.  At the same time eliminate the old implementation
restriction that DISTINCT was only supported for single-argument aggregates.
 
Possibly release-notable behavioral change: formerly, agg(DISTINCT x)
dropped null values of x unconditionally.  Now, it does so only if the
agg transition function is strict; otherwise nulls are treated as DISTINCT
normally would, ie, you get one copy.
 
Andrew Gierth, reviewed by Hitoshi Harada

Continue reading Waiting for 8.5 – ordered aggregates

Waiting for 8.5 – buffers info for explain

Today small, but (at least for me) really useful patch. Committed on 15th of December by Robert Haas, and written by Itagaki Takahiro, this patch does:

Log Message:
-----------
Add an EXPLAIN (BUFFERS) option to show buffer-usage statistics.
 
This patch also removes buffer-usage statistics from the track_counts
output, since this (or the global server statistics) is deemed to be a better
interface to this information.
 
Itagaki Takahiro, reviewed by Euler Taveira de Oliveira.

Continue reading Waiting for 8.5 – buffers info for explain

Waiting for 8.5 – exclusion constraints

On 7th of December, Tom Lane committed patch by Jeff Davis that adds general exclusion constraints:

Log Message:
-----------
Add exclusion constraints, which generalize the concept of uniqueness to
support any indexable commutative operator, not just equality.  Two rows
violate the exclusion constraint if "row1.col OP row2.col" is TRUE for
each of the columns in the constraint.
 
Jeff Davis, reviewed by Robert Haas

Continue reading Waiting for 8.5 – exclusion constraints