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Grouping sets

From: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
To: PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Grouping sets
Date: 2009-10-29 08:48:46
Message-ID: 162867790910290148m4bc7b050p966cf1668b19b74e@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
Hello

I got a possibility to continue on GROUPING SETS see
http://wiki.postgresql.org/wiki/Grouping_Sets

My last patch was based on an sharing functionality with non recursive
CTE. I would to recapitulate all options here and I would to prepare
this patch for next commitfest.

a) using actualised patch - review:
http://archives.postgresql.org/message-id/162867790811240316y52227d88xe53527399b329e05@mail.gmail.com
  + it is simple (share lot of code)
  + it is near to natural implementation - result is in "good" order
  + allows full implementation of ANSI SQL syntax - GROUP BY
[>>ALL<<|DISTINCT] GROUPING SETS(..
  - is serial
  - I read some objections - "it is only syntactic sugar"

b) modification of a (directly using tuple store without CTE code)
  + add some new code
  - it isn't syntactic sugar

c) go back to my first patch and use "feeders"
  - add some complexity to GROUP BY planner ( :-( )
  +/- add new concept to PostgreSQL - semi parallel execution
  - when datatype isn't hashable, then have to use serial processing
  - have to solve some corner behave of our hashtable support
  - should be very fast

I still prefer option a (with some cleaning)

I invite any comments and helpers.

Regards
Pavel Stehule

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Next:From: Hannu KrosingDate: 2009-10-29 08:54:24
Subject: Re: [PATCHES] updated hash functions for postgresql v1
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Subject: Re: Proposal - temporal contrib module

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