Query taking forever

JehanJaleel · #1 (**permalink**) 10-25-10, 18:43

Hi all,

The following query is taking forever to run on DB2...

select count (*) from SONG_KNOWLEDGE_BASE where SONG_CD not in (select SONG_CD from SONG)

It looks simple. I have heard that NOT IN should not be used, is this true. Can someone help me rewrite this query?

Thanks much,
Jehan

dav1mo · #2 (**permalink**) 10-26-10, 00:04

You could try something like this, it should perform better

Code:

select count (*)
  from SONG_KNOWLEDGE_BASE  skb
where not exists (select 1 
                           from SONG s
                        where skb.SONG_CD =s.SONG_CD)

Having indexes on SONG_CD will help as well.
Dave

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