Michael Fuhr <mike@fuhr.org> writes:
> ALTER INDEX indexname ALTER COLUMN "the expression" SET STATISTICS 100;
Yeah, that could probably be made to work.
> I do see that indexes allow multiple instances of the same expression,
> so this approach could be ambiguous.
I can't think of an actual use for that, though, so we could just ignore
the possible ambiguity. Or we could have the ALTER update all columns
matching the given expression.
> test=> CREATE INDEX foo1_idx ON foo (x, x);
> ERROR: duplicate key violates unique constraint "pg_attribute_relid_attnam_index"
Hmm, seems like there should be a more direct check for this ...
regards, tom lane