On 2/9/18 09:42, Tom Lane wrote: > Meh. It doesn't look significantly different to me than the restriction > that you can't have sub-selects in CHECK expressions, index expressions, > etc. Obviously we need a clean failure like you get for those cases. > But otherwise it's an OK restriction that stems from exactly the same > cause: we do not want to invoke the full planner in this context (and > even if we did, we don't want to use the full executor to execute the > result).
A close analogy is that EXECUTE parameters also don't accept subqueries. It would perhaps be nice if that could be made to work, but as discussed it would require a bunch more work. -- Peter Eisentraut http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
