On Wed, Mar 23, 2011 at 3:49 PM, Adarsh Sharma <adarsh.sha...@orkash.com>wrote:
> Vitalii Tymchyshyn wrote: > > 23.03.11 12:10, Adarsh Sharma написав(ла): > > I just want to retrieve that id 's from page_content which do not have any > entry in clause2 table. > > Then > select distinct(p.crawled_page_id) from page_content p > where NOT EXISTS (select 1 from clause2 c where c.source_id = > p.crawled_page_id); > is correct query. > > > I can't understand how* select 1 from clause2 c where c.source_id = > p.crawled_page_id works too, *i get my output . > > What is the significance of 1 here. > > Thanks , Adarsh > ** > > Best regards, Vitalii Tymchyshyn. > > > Its the inverted logic for finding crawled_page_id not matching with source_id. Actually, the idea was to force index scan on clause2 though. -- Regards, Chetan Suttraway EnterpriseDB <http://www.enterprisedb.com/>, The Enterprise PostgreSQL<http://www.enterprisedb.com/> company.
