[HACKERS] Performing antijoin in postgres

[Suresh_]

I want to add an antijoin operator to PostgreSql.  Basically I want to store
the result (tupletableslot) of one join and then compare it with
another..How do I store these results  and how do I compare them ?
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Re: [HACKERS] Performing antijoin in postgres

[Suresh_]

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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