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Re: nested select query failing

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "amol" <amol(at)mithi(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: nested select query failing
Date: 2003-05-20 15:18:26
Message-ID: 29058.1053443906@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-performance
"amol" <amol(at)mithi(dot)com> writes:
> explain analyze select attached_info.id from attached_tag_list,
> attached_info
> where
>          attached_tag_list.attached_tag = 265
>          and
>          attached_tag_list.id = attached_info.id

> NOTICE:  QUERY PLAN:

> Nested Loop  (cost=0.00..165349.50 rows=114 width=16) (actual
> time=117.14..8994.60 rows=15 loops=1)
>   ->  Index Scan using ix_attached_tag_list_id on attached_tag_list
> (cost=0.00..111.13 rows=96 width=12) (actual time=0.12..0.66 rows=15
> loops=1)
>   ->  Seq Scan on attached_info  (cost=0.00..1211.53 rows=33553 width=4)
> (actual time=3.67..197.98 rows=33553 loops=15)
> Total runtime: 8994.92 msec

> - I have already indexed attached_info on id using following query
> CREATE  INDEX attached_info_Index_1 ON attached_info(id) ;

Hm.  I'd have expected an index scan too.  Maybe the two id columns are
not of the same datatype?

			regards, tom lane

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