Re: BUG #17700: An assert failed in prepjointree.c

 

Thanks for the report! I can reproduce this issue on HEAD.

I haven't got too much time looking into it.  But the comment near the
assertion failure that says

 * Unlike the LEFT/RIGHT cases, we just Assert that there are
 * no PHVs that need to be evaluated at the semijoin's RHS,
 * since the rest of the query couldn't reference any outputs
 * of the semijoin's RHS.

I doubt this is true as a semijoin's qual can actually reference its
RHS.  In this case the assertion failure happens because there is PHV in
the join's qual.

I tried the change as to also check for PHVs that have to be evaluated
in the semijoin's RHS, like how we do for left/right join, and it can
avoid the assertion failure.  But I'm not sure if this is a reasonable
fix.

Thanks
Richard