Re: [HACKERS] generate_series regression 9.6->10

Paul Ramsey <pramsey@cleverelephant.ca> writes:
> The behaviour of generate_series seems to have changed a little, at least
> in conjunction w/ CTEs.

What's changed is the behavior of multiple SRFs in a SELECT's targetlist,
cf

https://git.postgresql.org/gitweb/?p=postgresql.git&a=commitdiff&h=69f4b9c85f168ae006929eec44fc44d569e846b9

specifically this comment:

    While moving SRF evaluation to ProjectSet would allow to retain the old
    "least common multiple" behavior when multiple SRFs are present in one
    targetlist (i.e.  continue returning rows until all SRFs are at the end of
    their input at the same time), we decided to instead only return rows till
    all SRFs are exhausted, returning NULL for already exhausted ones.  We
    deemed the previous behavior to be too confusing, unexpected and actually
    not particularly useful.

I see the current v10 release notes have failed miserably at documenting
this :-(.  Will try to improve that.

                        regards, tom lane