Re: Expression index ignores column statistics target

Michael Fuhr <mike(at)fuhr(dot)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