Re: [HACKERS] BRIN indexes for MAX, MIN, ORDER BY?

2015-09-29 Thread Jeremy Harris
On 27/09/15 21:58, Gavin Wahl wrote: > Somewhat harder but still possible would be using BRIN indexes to > accelerate ORDER BY. This would require a sorting algorithm that can take > advantage of mostly-sorted inputs. You would sort the page ranges by their > minimum or maximum value, then feed

Re: [HACKERS] BRIN indexes for MAX, MIN, ORDER BY?

2015-09-29 Thread Simon Riggs
On 29 September 2015 at 13:20, Jeremy Harris wrote: > On 27/09/15 21:58, Gavin Wahl wrote: > > Somewhat harder but still possible would be using BRIN indexes to > > accelerate ORDER BY. This would require a sorting algorithm that can take > > advantage of mostly-sorted inputs.

Re: [HACKERS] BRIN indexes for MAX, MIN, ORDER BY?

2015-09-28 Thread Marti Raudsepp
Hi Gavin Note that Alexander Korotkov already started work in 2013 on a somewhat similar feature called partial sort: http://www.postgresql.org/message-id/CAPpHfdscOX5an71nHd8WSUH6GNOCf=V7wgDaTXdDd9=gon-...@mail.gmail.com In particular, see the 2nd patch for KNN sort -- it uses known bounding

Re: [HACKERS] BRIN indexes for MAX, MIN, ORDER BY?

2015-09-28 Thread Heikki Linnakangas
On 09/28/2015 05:28 PM, Marti Raudsepp wrote: Note that Alexander Korotkov already started work in 2013 on a somewhat similar feature called partial sort: http://www.postgresql.org/message-id/CAPpHfdscOX5an71nHd8WSUH6GNOCf=V7wgDaTXdDd9=gon-...@mail.gmail.com In particular, see the 2nd patch for

Re: [HACKERS] BRIN indexes for MAX, MIN, ORDER BY?

2015-09-27 Thread Tom Lane
Alvaro Herrera writes: > Gavin Wahl wrote: >> It seems trivial to accelerate a MAX or MIN query with a BRIN index. You >> just find the page range with the largest/smallest value, and then only >> scan that one. Would that be hard to implement? I'm interested in working

Re: [HACKERS] BRIN indexes for MAX, MIN, ORDER BY?

2015-09-27 Thread Alvaro Herrera
Gavin Wahl wrote: > It seems trivial to accelerate a MAX or MIN query with a BRIN index. You > just find the page range with the largest/smallest value, and then only > scan that one. Would that be hard to implement? I'm interested in working > on it if someone can give me some pointers. I think

[HACKERS] BRIN indexes for MAX, MIN, ORDER BY?

2015-09-27 Thread Gavin Wahl
It seems trivial to accelerate a MAX or MIN query with a BRIN index. You just find the page range with the largest/smallest value, and then only scan that one. Would that be hard to implement? I'm interested in working on it if someone can give me some pointers. Somewhat harder but still possible

Re: [HACKERS] BRIN indexes for MAX, MIN, ORDER BY?

2015-09-27 Thread Thomas Munro
On Mon, Sep 28, 2015 at 9:58 AM, Gavin Wahl wrote: > It seems trivial to accelerate a MAX or MIN query with a BRIN index. You > just find the page range with the largest/smallest value, and then only scan > that one. You might need to scan more than that if you don't find

Re: [HACKERS] BRIN indexes for MAX, MIN, ORDER BY?

2015-09-27 Thread Gavin Wahl
> Yeah. I would urgently recommend that people *not* try to build new > things like planagg.c right now. A large part of the point of upper > planner path-ification is to have a less grotty way of dealing with > things like specialized aggregate implementations. Ok. I will wait and ask again