Re: Any way to favor index scans, but not bitmap index scans?
| От | Francisco Reyes |
|---|---|
| Тема | Re: Any way to favor index scans, but not bitmap index scans? |
| Дата | |
| Msg-id | c76fec09f01dcea1bea994d67b67c067@stringsutils.com обсуждение исходный текст |
| Ответ на | Re: Any way to favor index scans, but not bitmap index scans? ("Francisco Reyes" <lists@stringsutils.com>) |
| Список | pgsql-general |
On 4:12 pm 07/23/08 "Francisco Reyes" <lists@stringsutils.com> wrote:
> Also, that plan is only 3 seconds.
Minor update.
A co-worker is using another DB.. and re-running my query after he did his
work.. now the query using the index scans takes 2 minutes instead of 3
seconds. 3 seconds was likely data cached.
To re-list the times..
Sequential scan 12 minutes
Bitmap scans 30 minutes
index scan with not bitmap 2 minutes
It is worth pointing out that the bitmap test was run AFTER the sequential
scan test.. right after it.. so it should have benefited from OS caching.
The join_ids table fits completely in memory.
select pg_size_pretty(pg_total_relation_size('join_ids'));
pg_size_pretty
----------------
291 MB
(1 row)
par4mo=# select pg_size_pretty(pg_relation_size('join_ids'));
pg_size_pretty
----------------
94 MB
(1 row)
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