Here are the two syntaxes we can use for turning off clustering:
1) ALTER TABLE / SET WITHOUT CLUSTER
This will turn off clusting on any index on the table that has it
enabled. It won't recurse so as to match the CLUSTER ON syntax.
However, this form makes the non-standardy SET WITHOUT form more
emphasised...
2) ALTER TABLE / DROP CLUSTER ON idx
I like this form, however to make it work, we need to bump CLUSTER to
being a reserved keyword. This form looks more like SQL standard, and
is related to the CLUSTER ON form.
Which one do we want?
Chris
