Re: implementing another hash join...

Martha Chronopoulou <mchron@aueb.gr> writes:
> Im new to postgres and I'm about to implement the algorithm "double 
> pipelined hash join". I've started using SPI functions but soon I 
> realised that  I 'm  not at the right way (am I?).

Not even close.  You need to be implementing new executor node types
(see backend/executor) and teaching the planner about the properties
of this join method.  SPI is at a completely different level of
abstraction ...

> Is there a way that I'm not obliged to change code of the optimizer of
> postgres

Nope.  The set of join types it knows about is pretty much hard-wired.
        regards, tom lane