On Mon, May 11, 2020 at 4:22 PM Tom Lane <t...@sss.pgh.pa.us> wrote: > Robert Haas <robertmh...@gmail.com> writes: > > If the parent is RTI 1, and the children are RTIs 2..6, what > > varno/varattno will we use in RTI 1's tlist to represent a column that > > exists in both RTI 2 and RTI 3 but not in RTI 1, 4, 5, or 6? > > Fair question. We don't have any problem representing the column > as it exists in any one of those children, but we lack a notation > for the "union" or whatever you want to call it, except in the case > where the parent relation has a corresponding column. Still, this > doesn't seem that hard to fix. My inclination would be to invent > dummy parent-rel columns (possibly with negative attnums? not sure if > that'd be easier or harder than adding them in the positive direction) > to represent such "union" columns.
Ah, that makes sense. If we can invent dummy columns on the parent rel, then most of what I was worrying about no longer seems very worrying. I'm not sure what's involved in inventing such dummy columns, though. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
