Are (any of) these patches targetting v16 ? typos: ar we - we are? morestly - mostly interstect - intersect
> + * XXX We don't sort the bins, so just do binary sort. For large number of > values > + * this might be an issue, for small number of values a linear search is > fine. "binary sort" is wrong? > + * only half of there ranges, thus 1/2. This can be extended to randomly half of *these* ranges ? > From 7b3307c27b35ece119feab4891f03749250e454b Mon Sep 17 00:00:00 2001 > From: Tomas Vondra <tomas.von...@postgresql.org> > Date: Mon, 17 Oct 2022 18:39:28 +0200 > Subject: [PATCH 01/11] Allow index AMs to build and use custom statistics I think the idea can also apply to btree - currently, correlation is considered to be a property of a column, but not an index. But that fails to distinguish between a freshly built index, and an index with out of order heap references, which can cause an index scan to be a lot more expensive. I implemented per-index correlation stats way back when: https://www.postgresql.org/message-id/flat/20160524173914.GA11880%40telsasoft.com See also: https://www.postgresql.org/message-id/14438.1512499...@sss.pgh.pa.us With my old test case: Index scan is 3x slower than bitmap scan, but index scan is costed as being cheaper: postgres=# explain analyze SELECT * FROM t WHERE i>11 AND i<55; Index Scan using t_i_idx on t (cost=0.43..21153.74 rows=130912 width=8) (actual time=0.107..222.737 rows=128914 loops=1) postgres=# SET enable_indexscan =no; postgres=# explain analyze SELECT * FROM t WHERE i>11 AND i<55; Bitmap Heap Scan on t (cost=2834.28..26895.96 rows=130912 width=8) (actual time=16.830..69.860 rows=128914 loops=1) If it's clustered, then the index scan is almost twice as fast, and the costs are more consistent with the associated time. The planner assumes that the indexes are freshly built... postgres=# CLUSTER t USING t_i_idx ; postgres=# explain analyze SELECT * FROM t WHERE i>11 AND i<55; Index Scan using t_i_idx on t (cost=0.43..20121.74 rows=130912 width=8) (actual time=0.084..117.549 rows=128914 loops=1) -- Justin