=?ISO-8859-1?Q?Ott=F3_Havasv=F6lgyi?= <havasvolgyi(dot)otto(at)gmail(dot)com> writes:
> As far as I know SQL Server has some similar feature. It does not join
> if not necessary, more exactly: if the result would be the same if it
> joined the table.
I find it really really hard to believe that such cases arise often
enough to justify having the planner spend cycles checking for them.
regards, tom lane