Re: Question about indexing!

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От Stephan Szabo
Тема Re: Question about indexing!
Дата
Msg-id Pine.BSF.4.21.0110020927590.46517-100000@megazone23.bigpanda.com
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Ответ на Question about indexing!  (Jeong Jaeick, 정재익 <advance@advance.sarang.net>)
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On Tue, 2 Oct 2001, [euc-kr] Jeong Jaeick, ������ wrote:

> select * from pgsql_bbs where topic = 'qna' and deleted < 2 
>        order by gid desc, pos asc limit 20, 0;
> 
> But this query is not using index!
> 
> The next is result of explain of this query:
> 
> dsn=# explain select * from pgsql_bbs where topic = 'qna' and deleted < 2 
> dsn-#        order by gid desc, pos asc limit 20, 0;
> NOTICE:  QUERY PLAN:
> 
> Limit  (cost=15.71..15.71 rows=11 width=245)
>   ->  Sort  (cost=15.71..15.71 rows=11 width=245)
>         ->  Index Scan using pgsql_topic_deleted on pgsql_bbs  (cost=0.00..15.51 rows=11 width=245)

It appears to be using the topic_deleted index according to this 
explain output.
How many rows actually have topic='qna' and deleted<2?




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