PG Bug reporting form <noreply(at)postgresql(dot)org> writes:
> A cube expression index built with extra_float_digits = 0 returns no rows
> after the setting is changed to 3, while sequential evaluation of the same
> predicate returns one row. cube_out(cube) is marked IMMUTABLE, but the same
> cube value is rendered as (1.23456789012346) with the first setting and
> (1.2345678901234567) with the second.
Yeah. There's a wider discussion in progress about this class of
bugs, over here:
https://www.postgresql.org/message-id/flat/19644-d6db3fb5e5ad92f4%40postgresql.org
regards, tom lane