From: | Andreas Kretschmer <akretschmer(at)spamfence(dot)net> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | seq-scan or index-scan |
Date: | 2012-07-03 15:58:59 |
Message-ID: | 20120703155859.GA5956@tux |
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Thread: | |
Lists: | pgsql-general |
Dear list,
i have a table and i'm selecting all records without a where-condition, and i don't need a ORDER BY:
production=*# explain analyse select * from boxes;
QUERY PLAN
---------------------------------------------------------------------------------------------------------------
Seq Scan on boxes (cost=0.00..990783.99 rows=6499 width=581) (actual time=6.514..4588.136 rows=3060 loops=1)
Total runtime: 4588.729 ms
(2 rows)
It's slow, so i tried with an ORDER BY:
production=# explain analyse select * from boxes order by id;
QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------
Index Scan using boxes_pkey on boxes (cost=0.00..162437.00 rows=6499 width=581) (actual time=0.065..55.730 rows=3060 loops=1)
Total runtime: 56.169 ms
(2 rows)
Why not using the index (it's a primary key) for the first query?
PG 9.1.3
Andreas
--
Really, I'm not out to destroy Microsoft. That will just be a completely
unintentional side effect. (Linus Torvalds)
"If I was god, I would recompile penguin with --enable-fly." (unknown)
Kaufbach, Saxony, Germany, Europe. N 51.05082°, E 13.56889°
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