On 1/27/19 4:21 PM, Tom Lane wrote:
> Andrew Gierth <andrew@tao11.riddles.org.uk> writes:
>> I'm not sure we should nail down the rule that the absence of NOT
>> MATERIALIZED will mean a multiply-referenced CTE is evaluated once. One
>> would hope that in the future the planner might be taught to inline or
>> not in that case depending on cost. I think it makes more sense to say
>> that we never inline if MATERIALIZED is specified, that we always inline
>> if NOT MATERIALIZED is specified, and that if neither is specified the
>> planner will choose (but perhaps note that currently it always chooses
>> only based on refcount).
>
> I have no objection to documenting it like that; I just don't want us
> to go off into the weeds trying to actually implement something smarter
> for v12.
+1
Andreas