"Ioseph Kim" <pgsql-kr(at)postgresql(dot)or(dot)kr> writes:
> when @-@ operator used at path type,
> below query maybe returns 1.
> because this path is just line.
No, because it's a closed path, so it's a loop from (0,0) to (1,0)
and back again. If you don't want to count the return segment,
use an open path.
regards, tom lane