Jeff Davis <pgsql(at)j-davis(dot)com> writes:
> I tried to move the WHERE clause right before or after the
> index_parameters, but that resulted in shift/reduce conflicts.
You could avoid the conflicts in at least two ways:
* require parens around the WHERE expression
* stick the WHERE inside the EXCLUSION ( ... ) bit, so that its
expression is terminated by the outer right paren.
Not sure if either of these is less ugly than putting it at the end,
though :-(. They both seem a bit surprising.
regards, tom lane