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we extended the appendrel mechanism to support UNION ALL optimization. The reason nobody noticed was that we are not actually using attr_needed data for appendrel children; hence it seems more reasonable to rip it out than fix it. Back-patch to 8.2 because an Assert failure is possible in corner cases. Per examination of an example from Jim Nasby. In HEAD, also get rid of AppendRelInfo.col_mappings, which is quite inadequate to represent UNION ALL situations; depend entirely on translated_vars instead.