Re: 9.5 alpha: some small comments on BRIN and btree_gin

Marc Mamin wrote:

> - BRIN cost: I've made a silly test, where all distinct values exist in all BRIN page ranges:
>         
>     INSERT into tbrin_1 (cat_id, ....) SELECT s%20, ... FROM generate_series(1,3000000 )s;
>     CREATE INDEX cat_brin_1 on tbrin_1 using BRIN (cat_id)with (pages_per_range=64);
>     SELECT * from tbrin_1 WHERE cat_id=10; 
>        http://explain.depesz.com/s/9YQR
> 
>    There seems to be no "fence" against useless BRIN indexes that would allow a fallback on a table scan.
>    But the time overhead remind small :)

Hmm, I guess the costing function for brin could stand some improvement.
Clearly we're not covering all bases.

-- 
Álvaro Herrera                http://www.2ndQuadrant.com/
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