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 boxes from the GiST index for sorting, which in many ways is similar to min/max BRIN ranges. > *partial-knn-1.patch* > > KNN-GiST provides ability to get ordered results from index, but this order > is based only on index information. For instance, GiST index contains > bounding rectangles for polygons, and we can't get exact distance to > polygon from index (similar situation is in PostGIS). In attached patch, > GiST distance method can set recheck flag (similar to consistent method). > This flag means that distance method returned lower bound of distance and > we should recheck it from heap. Unfortunatley this work has stalled. Regards, Marti On Sun, Sep 27, 2015 at 11:58 PM, Gavin Wahl <gavinw...@gmail.com> 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. > > 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 the sorting algorithm in that order. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
