Re: Eliminating unnecessary left joins
Havasvölgyi Ottó <havasvolgyi.otto@gmail.com>
From: Ottó Havasvölgyi <havasvolgyi.otto@gmail.com>
To: pgsql-hackers@postgresql.org
Date: 2007-04-16T09:51:24Z
Lists: pgsql-hackers
Hi, Could you Bruce please add a TODO item for this feature? The description could look something like this: Eliminate the table T from the query/subquery if the following requirements are satisfied: 1. T is left joined 2. T is referenced only in the join expression where it is left joined 3. the left join's join expression is a simple equality expression like T1.C1=T2.C2; T1!=T2 and (T==T1 or T==T2) 4. the column of T in the join exression is the primary key of T ---------------------------------------------------- I hope it is comlete. I think this is the simplest case, so we should start with this. Thanks, Otto