Marti Raudsepp <ma...@juffo.org> writes:
> Is this just a planner shortcoming or a bug? Or is there some
> justification for this behavior?
Per the comment in is_safe_append_member():
* It's only safe to pull up the child if its jointree contains exactly
* one RTE, else the AppendRelInfo data structure breaks. The one base RTE
* could be buried in several levels of FromExpr, however.
*
* Also, the child can't have any WHERE quals because there's no place to
* put them in an appendrel. (This is a bit annoying...)
This will probably get fixed someday, but I wouldn't recommend holding
your breath for it.
regards, tom lane
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