Is there any way to tell the optimizer that my large, but simple-schema table are already sorted?

[WeiQi Huang]

Is there any way(i mean something like index hints) to tell the optimizer that my large, but simple-schema table is already sorted?

So as to save my running-time and storage cost to create an full coverage index.


Use case:

Tables:
X(a int, b int, c int);
Y(a int, b int, c int);

then, i use a natural-join query to find out whether these two table are exactly same:

SELECT count(*) FROM X join Y using(a,b) WHERE X.c <> Y.c;