Re: [HACKERS] "ExecInitIndexScan: both left and right..." meaning?

Ed Loehr wrote:

> Are there any known consequences of forbidding nestloop joins?  Performance
> hits?  Functionality hits?

OK, I pulled out my old RDBMS text.  Here are my current assumptions re join
strategies:

1)  The only Pgsql alternative join strategies to nested-loop joins are merge
join and hash join.

2)  Merge join only makes sense if the data is physically ordered by the join
keys, and there is almost always a natural entropy away from physical sort
order.

Therefore, it generally makes sense to use only hash join.

Are my assumptions correct?  Reasonable conclusion?

Can I configure psql to use only hash joins?

Cheers,
Ed Loehr