Re: WIP: Covering + unique indexes.

13.01.2016 04:27, David Rowley:

I've also done some testing:

create table ab (a int, b int);
insert into ab select a,b from generate_Series(1,10) a(a), generate_series(1,10000) b(b);
set enable_bitmapscan=off;
set enable_indexscan=off;

select * from ab where a = 1 and b=1;
 a | b
---+---
 1 | 1
(1 row)

set enable_indexscan = on;
select * from ab where a = 1 and b=1;
 a | b
---+---
(0 rows)

This is broken. I've not looked into why yet, but from looking at the EXPLAIN output I was a bit surprised to see b=1 as an index condition. I'd have expected a Filter maybe, but I've not looked at the EXPLAIN code to see how those are determined yet.

Hmm... Do you use both patches?
And could you provide index definition, I can't reproduce the problem assuming that index is created by the statement
CREATE INDEX idx ON ab (a) INCLUDING (b);