Month: April 2015

Waiting for 9.5 – Reduce lock levels of some trigger DDL and add FKs

On 5th of April, Simon Riggs committed patch:

Reduce lock levels of some trigger DDL and add FKs
 
Reduce lock levels to ShareRowExclusive for the following SQL
 CREATE TRIGGER (but not DROP or ALTER)
 ALTER TABLE ENABLE TRIGGER
 ALTER TABLE DISABLE TRIGGER
 ALTER TABLE … ADD CONSTRAINT FOREIGN KEY
 
Original work by Simon Riggs, extracted and refreshed by Andreas Karlsson
New test cases added by Andreas Karlsson
Reviewed by Noah Misch, Andres Freund, Michael Paquier and Simon Riggs

Continue reading Waiting for 9.5 – Reduce lock levels of some trigger DDL and add FKs

Waiting for 9.5 – Add stats for min, max, mean, stddev times to pg_stat_statements.

On 27th of March, Andrew Dunstan committed patch:

Add stats for min, max, mean, stddev times to pg_stat_statements.
 
The new fields are min_time, max_time, mean_time and stddev_time.
 
Based on an original patch from Mitsumasa KONDO, modified by me. Reviewed by Petr Jelínek.

Continue reading Waiting for 9.5 – Add stats for min, max, mean, stddev times to pg_stat_statements.

Waiting for 9.5 – Add support for index-only scans in GiST.

On 26th of March, Heikki Linnakangas committed patch:

Add support for index-only scans in GiST.
 
This adds a new GiST opclass method, 'fetch', which is used to reconstruct
the original Datum from the value stored in the index. Also, the 'canreturn'
index AM interface function gains a new 'attno' argument. That makes it
possible to use index-only scans on a multi-column index where some of the
opclasses support index-only scans but some do not.
 
This patch adds support in the box and point opclasses. Other opclasses
can added later as follow-on patches (btree_gist would be particularly
interesting).
 
Anastasia Lubennikova, with additional fixes and modifications by me.

Continue reading Waiting for 9.5 – Add support for index-only scans in GiST.

Waiting for 9.5 – Add pg_rewind, for re-synchronizing a master server after failback.

On 23rd of March, Heikki Linnakangas committed patch:

Add pg_rewind, for re-synchronizing a master server after failback.
 
Earlier versions of this tool were available (and still are) on github.
 
Thanks to Michael Paquier, Alvaro Herrera, Peter Eisentraut, Amit Kapila,
and Satoshi Nagayasu for review.

Continue reading Waiting for 9.5 – Add pg_rewind, for re-synchronizing a master server after failback.

Waiting for 9.5 – Allow foreign tables to participate in inheritance. – A.K.A. PostgreSQL got sharding.

On 22nd of March, Tom Lane committed patch:

Allow foreign tables to participate in inheritance.
 
Foreign tables can now be inheritance children, or parents.  Much of the
system was already ready for this, but we had to fix a few things of
course, mostly in the area of planner and executor handling of row locks.
 
As side effects of this, allow foreign tables to have NOT VALID CHECK
constraints (and hence to accept ALTER ... VALIDATE CONSTRAINT), and to
accept ALTER SET STORAGE and ALTER SET WITH/WITHOUT OIDS.  Continuing to
disallow these things would've required bizarre and inconsistent special
cases in inheritance behavior.  Since foreign tables don't enforce CHECK
constraints anyway, a NOT VALID one is a complete no-op, but that doesn't
mean we shouldn't allow it.  And it's possible that some FDWs might have
use for SET STORAGE or SET WITH OIDS, though doubtless they will be no-ops
for most.
 
An additional change in support of this is that when a ModifyTable node
has multiple target tables, they will all now be explicitly identified
in EXPLAIN output, for example:
 
 Update on pt1  (cost=0.00..321.05 rows=3541 width=46)
   Update on pt1
   Foreign Update on ft1
   Foreign Update on ft2
   Update on child3
   ->  Seq Scan on pt1  (cost=0.00..0.00 rows=1 width=46)
   ->  Foreign Scan on ft1  (cost=100.00..148.03 rows=1170 width=46)
   ->  Foreign Scan on ft2  (cost=100.00..148.03 rows=1170 width=46)
   ->  Seq Scan on child3  (cost=0.00..25.00 rows=1200 width=46)
 
This was done mainly to provide an unambiguous place to attach "Remote SQL"
fields, but it is useful for inherited updates even when no foreign tables
are involved.
 
Shigeru Hanada and Etsuro Fujita, reviewed by Ashutosh Bapat and Kyotaro
Horiguchi, some additional hacking by me

Continue reading Waiting for 9.5 – Allow foreign tables to participate in inheritance. – A.K.A. PostgreSQL got sharding.

Waiting for 9.5 – Use 128-bit math to accelerate some aggregation functions.

On 20th of March, Andres Freund committed patch:

Use 128-bit math to accelerate some aggregation functions.
 
On platforms where we support 128bit integers, use them to implement
faster transition functions for sum(int8), avg(int8),
var_*(int2/int4),stdev_*(int2/int4). Where not supported continue to use
numeric as a transition type.
 
In some synthetic benchmarks this has been shown to provide significant
speedups.
 
Bumps catversion.
 
Discussion: 544BB5F1.50709@proxel.se
Author: Andreas Karlsson
Reviewed-By: Peter Geoghegan, Petr Jelinek, Andres Freund, Oskari Saarenmaa, David Rowley

Continue reading Waiting for 9.5 – Use 128-bit math to accelerate some aggregation functions.