Re: [GENERAL] function indexes, index only scan and sorting

2014-12-12 Thread Tom Lane
Jonathan Vanasco writes: > Thank you so much for posting this test. > I got a seq scan on my local machine, so I checked the version... still > running 9.2.4. > I tried it on production (which is 9.3.x) and got the same result as you. Hmm, well, I get the same result from 9.2.9, as well as ever

Re: [GENERAL] function indexes, index only scan and sorting

2014-12-12 Thread Jonathan Vanasco
On Dec 12, 2014, at 4:58 PM, Tom Lane wrote: > regression=# create table tt (f1 int, f2 text); > CREATE TABLE > regression=# create index on tt (lower(f2)); > CREATE INDEX > regression=# explain select * from tt order by lower(f2); > QUERY PLAN

Re: [GENERAL] function indexes, index only scan and sorting

2014-12-12 Thread Tom Lane
Jonathan Vanasco writes: > Am I correct in observing that the value of a function index can't be used > for sorting ? No ... regression=# create table tt (f1 int, f2 text); CREATE TABLE regression=# create index on tt (lower(f2)); CREATE INDEX regression=# explain select * from tt order by lowe

[GENERAL] function indexes, index only scan and sorting

2014-12-12 Thread Jonathan Vanasco
Can someone confirm a suspicion for me ? I have a moderately sized table (20+ columns, 3MM rows) that tracks "tags". I have a lower(column) function index that is used simplify case-insensitive lookups. CREATE INDEX idx_tag_name_lower ON tag(lower(name)); I have a few complex queries