Re: Reason of Slowness of query

Vitalii Tymchyshyn <tivv00@xxxxxxxxx> · Wed, 23 Mar 2011 09:25:34 +0200



    23.03.11 08:28, Adarsh Sharma написав(ла):
    
      
      I perform a join query on it as :

      
       explain analyze select distinct(p.crawled_page_id) from
        page_content p , clause2  c where p.crawled_page_id !=
        c.source_id ;

    
    Your query is wrong. This query will return every crawled_page_id
    if clause2 has more then 1 source_id. This is because DB will be
    able to find clause with source_id different from crawled_page_id.
    You need to use "not exists" or "not in".

    
    Best regards, Vitalii Tymchyshyn.