Search Postgresql Archives

Re: index scan leads to result that is different from sec scan after upgrading to 8.3.4

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Sorry, I forget to paste explains

> explain showed that first query do index scan and second one sec scan.
>

db_online=> select obj_status_did, count(1) from person_online
where obj_status_did = 1 group by obj_status_did;
                                                        QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------
 GroupAggregate  (cost=0.00..36.37 rows=1 width=2) (actual
time=1.169..1.170 rows=1 loops=1)
   ->  Index Scan using i_person_online_test__geo_point on
person_online_test  (cost=0.00..30.07 rows=1258 width=2) (actual
time=0.016..0.928 rows=258 loops=1)
 Total runtime: 1.268 ms
(3 rows)

db_online=> select obj_status_did, count(1) from person_online
group by obj_status_did;
                                                       QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------
 HashAggregate  (cost=302.87..302.88 rows=1 width=2) (actual
time=0.668..0.669 rows=1 loops=1)
   ->  Seq Scan on person_online_test  (cost=0.00..296.58 rows=1258
width=2) (actual time=0.009..0.372 rows=258 loops=1)
 Total runtime: 0.754 ms
(3 rows)


-- 
Regards,
Sergey Konoplev
--
PostgreSQL articles in english & russian
http://gray-hemp.blogspot.com/search/label/postgresql/

-- 
Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Postgresql Jobs]     [Postgresql Admin]     [Postgresql Performance]     [Linux Clusters]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Postgresql & PHP]     [Yosemite]
  Powered by Linux