Re: Expression index can get an empty generated column name

Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
> Hmm, yeah, that's not great, although I'd argue that the real issue in
> this particular example is that we should treat the whole-row Var as
> being named "t" rather than being ignored. Still, installing a
> fallback of "expr" isn't a bad idea.

good idea! A whole-row Var now contributes the relation's name, and
"expr" remains as a fallback for expressions that still yield no text
(e.g. a constant that sanitizes away to nothing).

CREATE TABLE t (a int, b int);
CREATE INDEX ON t ((t IS NOT NULL)); -- index t_t_idx, column "t"
CREATE INDEX ON t ((','::text)); -- index t_expr_idx, column
"expr"
CREATE INDEX ON t ((a + b)); -- index t_a_b_idx, column "a_b"

Regression test updated. make check is green.

Patch is attached.

Thanks,
Dhruv