Every now and then I need a function that returns nothing.
As you perhaps know, even defining function as “RETURNS VOID" doesn't fully solve the problem:
Continue reading Tips n' Tricks – return nothing from PL/PgSQL function
Find cheapest combination of rooms in hotels
Today, on Stack Overflow there was interesting question.
Generally, given table that looks like this:
room | people | price | hotel 1 | 1 | 200 | A 2 | 2 | 99 | A 3 | 3 | 95 | A 4 | 1 | 90 | B 5 | 6 | 300 | B
Find cheapest combination of rooms that would accomodate given number of guests.
Continue reading Find cheapest combination of rooms in hotels
Big changes on explain.depesz.com
Today, I released 2 new versions (new features in 0.5, and then quick bugfix in 0.51) of Pg::Explain Perl library.
This is the base of explain.depesz.com – the code that does heavy lifting of parsing plans, and providing them in uniform way (object).
Waiting for 9.1 – Synchronous replication
On 6th of March, Simon Riggs committed patch:
Efficient transaction-controlled synchronous replication. If a standby is broadcasting reply messages and we have named one or more standbys in synchronous_standby_names then allow users who set synchronous_replication to wait for commit, which then provides strict data integrity guarantees. Design avoids sending and receiving transaction state information so minimises bookkeeping overheads. We synchronize with the highest priority standby that is connected and ready to synchronize. Other standbys can be defined to takeover in case of standby failure. This version has very strict behaviour; more relaxed options may be added at a later date. Simon Riggs and Fujii Masao, with reviews by Yeb Havinga, Jaime Casanova, Heikki Linnakangas and Robert Haas, plus the assistance of many other design reviewers.
Waiting for 9.1 – Writable CTE
On 25th of February, Tom Lane committed patch:
Support data-modifying commands (INSERT/UPDATE/DELETE) IN WITH. This patch implements data-modifying WITH queries according TO the semantics that the updates ALL happen WITH the same command counter VALUE, AND IN an unspecified ORDER. Therefore one WITH clause can't see the effects of another, nor can the outer query see the effects other than through the RETURNING values. And attempts to do conflicting updates will have unpredictable results. We'll need TO document ALL that. This commit just fixes the code; documentation updates are waiting ON author. Marko Tiikkaja AND Hitoshi Harada
explain.depesz.com version 2.0
Thanks to enormous work done by Łukasz ‘metys' Lewandowski, explain.depesz.com page is no longer “desiged by depesz" (which is a code for “ugly as hell"), but is nice, and good looking.
If you like it, please do send some thank you note to Łukasz – he blogs in Polish, but he reads and understands English too.
Change is not only skin deep. The whole site has been rewritten, and uses now Mojolicious web framework instead of Catalyst.
This change should be a welcome surprise to anyone willing to setup their own copy of the site for top-secret plans from their company – mostly because number of dependencies dropped significantly.
All in all – have fun, and thanks for using the site.
Waiting for 9.1 – Foreign data wrapper
Well, saying that on particular date someone committed patch, wouldn't be really telling. In fact various bits and pieces of underlying logic have been committed for a long time, but now we finally have some functionality visible and available to end users.
This became the case thanks to these two commits, both committed on 20th of February, by Tom Lane.
Implement an API to let foreign-data wrappers actually be functional. This commit provides the core code and documentation needed. A contrib module test case will follow shortly. Shigeru Hanada, Jan Urbanski, Heikki Linnakangas
and second:
Add contrib/file_fdw foreign-data wrapper for reading files via COPY. This is both very useful in its own right, and an important test case for the core FDW support. This commit includes a small refactoring of copy.c to expose its option checking code as a separately callable function. The original patch submission duplicated hundreds of lines of that code, which seemed pretty unmaintainable. Shigeru Hanada, reviewed by Itagaki Takahiro and Tom Lane
Waiting for 9.1 – Transaction level advisory locks
On 18th of February, Itagaki Takahiro committed patch:
Add transaction-level advisory locks. They share the same locking namespace with the existing session-level advisory locks, but they are automatically released at the end of the current transaction and cannot be released explicitly via unlock functions. Marko Tiikkaja, reviewed by me.
Continue reading Waiting for 9.1 – Transaction level advisory locks
Waiting for 9.1 – Arrays in PL/Perl
On 18th of February, Alvaro Herrera committed patch:
Convert Postgres arrays to Perl arrays on PL/perl input arguments More generally, arrays are turned in Perl array references, and row and composite types are turned into Perl hash references. This is done recursively, in a way that's natural to every Perl programmer. To avoid a backwards compatibility hit, the string representation of each structure is also available if the function requests it. Authors: Alexey Klyukin and Alex Hunsaker. Some code cleanups by me.
Waiting for 9.1 – FOREACH IN ARRAY
On 16th of February, Tom Lane committed patch:
Add FOREACH IN ARRAY looping to plpgsql. (I'm not entirely sure that we've finished bikeshedding the syntax details, but the functionality seems OK.) Pavel Stehule, reviewed by Stephen Frost and Tom Lane