Re: Performing antijoin in postgres

Thanks for the reply. I can do this at the higher level; but this antijoin
thing is a small part of a bigger project. So I want to do it internally in
one of the joins. Does anyone have experience in storing tupleslpts and
comparing them ??



Gregory Stark wrote:
> 
> "Suresh_" <[email protected]> writes:
> 
>> I want to add an antijoin operator to PostgreSql.  
> 
> I think you can already do what you want like this:
> 
> SELECT *
>   FROM A FULL OUTER JOIN B ON (x=y)
>  WHERE x IS NULL
>     OR y IS NULL
> 
> So for example:
> 
> postgres=# select * from a;
>  i 
> ---
>  1
>  2
> (2 rows)
> 
> postgres=# select * from b;
>  i 
> ---
>  2
>  3
> (2 rows)
> 
> postgres=# select * from a full outer join b on (a.i=b.i) where a.i is
> null or b.i is null;
>  i | i 
> ---+---
>  1 |  
>    | 3
> (2 rows)
> 
> -- 
>   Gregory Stark
>   EnterpriseDB          http://www.enterprisedb.com
> 
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> TIP 6: explain analyze is your friend
> 
> 

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