On May 29, 2008, at 6:08 PM, Jan Urbański wrote:
Now about the idea itself:
http://www.informatik.uni-augsburg.de/de/lehrstuehle/dbis/db/
publications/all_db_tech-reports/tr-2001-7_kie_koe/
tr-2001-7_kie_koe.pdf
That's one of the basic papers about Preference SQL, explaining
what it's all
Decibel! wrote:
On May 29, 2008, at 6:08 PM, Jan Urbański wrote:
Preference SQL is an extension to regular SQL, that allows expressing
preferences in SQL queries. Preferences are like soft WHERE clauses.
This seems like a subset of http://pgfoundry.org/projects/qbe/ ... or do
I
Jan,
I'm still working on producing a comparision of preference SQL and the
skyline operator, more to follow soon.
The big problem with all of these is that there's no standards on
approximate queries yet. So we're reluctant to support syntax extensions
for them.
--
--Josh
Josh Berkus
Josh Berkus wrote:
Jan,
I'm still working on producing a comparision of preference SQL and the
skyline operator, more to follow soon.
The big problem with all of these is that there's no standards on
approximate queries yet. So we're reluctant to support syntax extensions
for them.
Yes,
Jan Urbański wrote:
Maybe I should talk to my thesis supervisor and find out if
implementing window functions would be an equally good subject...
I suppose having window functions would be a nice thing? To be honest
- I need a thesis subject and I like fiddling with Postgres.
Window
Jan Urba??ski wrote:
Preference SQL is an extension to regular SQL, that allows expressing
preferences in SQL queries. Preferences are like soft WHERE clauses. A
preference doesn't need to be satisfied by a tuple for it to appear in
the result set, but it's preferred it is. More strictly, a set
Stephen R. van den Berg wrote:
Jan Urbański wrote:
An example of a preference query would be (quoting the linked PDF):
SELECT * FROM programmers PREFERRING exp IN ('java', 'C++');
or
SELECT * FROM computers
PREFERRING HIGHEST(main_memory) AND HIGHEST(cpu_speed);
Forgive my ignorance, but
den Berg
Cc: Postgres - Hackers
Subject: Re: [HACKERS] proposal: Preference SQL
Stephen R. van den Berg wrote:
Jan Urbański wrote:
An example of a preference query would be (quoting the linked PDF):
SELECT * FROM programmers PREFERRING exp IN ('java', 'C++'); or
SELECT * FROM computers
Jan Urbański wrote:
SELECT * FROM computers
PREFERRING HIGHEST(main_memory) AND HIGHEST(cpu_speed);
This seems similar to the SKYLINE OF patch that was discussed a year (?)
ago. Are you familiar with that project? Can you summarize the differences?
--
Heikki Linnakangas
EnterpriseDB
Kevin Walker wrote:
Yes, the preference clause can be rewritten using standard SQL. The syntax to duplicate the example result set is listed below. The syntax is not very flexible or easy to read.
select id
from computer
where (main_memory = (select max(main_memory)
Heikki Linnakangas wrote:
Jan Urbański wrote:
SELECT * FROM computers
PREFERRING HIGHEST(main_memory) AND HIGHEST(cpu_speed);
This seems similar to the SKYLINE OF patch that was discussed a year (?)
ago. Are you familiar with that project? Can you summarize the differences?
Oh, I wasn't
you proposed was easier to read and more
flexible.
Kevin
Date: Sat, 31 May 2008 16:53:54 +0200
From: [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
CC: [EMAIL PROTECTED]; pgsql-hackers@postgresql.org
Subject: Re: [HACKERS] proposal: Preference SQL
Kevin Walker wrote:
Yes, the preference
This is a proposal of a non-standard, albeit useful functionality in
Postgres (it is also a quite long email message).
Background:
I'm currently working on a GSoC project for PostgreSQL
(http://wiki.postgresql.org/wiki/Gsoc08-tss). But at the same time, I'm
now at the point where I need to
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