Re: EXPLAIN ANALYZE of BRIN bitmap index scan with disjunction
Justin Pryzby <[email protected]>
| Newsgroups | gmane.comp.db.postgresql.performance |
|---|---|
| Message-ID | <[email protected]> |
On Thu, Jun 20, 2019 at 12:09:13PM -0600, Michael Lewis wrote:
> For kicks I tried the example given and got the below which seems more
> expected.
Do you just mean that it ran faster the 2nd time ? Isn't that just due just to
cache effects ? Rerun them both back to back.
See that the "actual" rowcount of the Index Scan is higher with tigher
condition:
> -> Bitmap Index Scan on idx_brin_test_brin (cost=0.00..3.32 rows=14286 width=0) (actual time=0.018..0.019 rows=640 loops=1)
> Index Cond: (id >= 90000)
> -> Bitmap Index Scan on idx_brin_test_brin (cost=0.00..3.31 rows=7143 width=0) (actual time=0.026..0.027 rows=1280 loops=1)
> Index Cond: ((id >= 90000) AND (r = ANY ('{1,3}'::integer[])))