Cartesian join: What is this BUFFER SORT accomplishing?

Hi,

I'm performing a (intended) cartesian join of a table of one row, to a big table (9.2.0.5 on Open VMS):

SELECT *
FROM one_row_table, big_table.

This is the EXPLAIN PLAN:

SELECT STATEMENT

	MERGE JOIN CARTESIAN
		TABLE ACCESS FULL one_row_table
		BUFFER SORT
			TABLE ACCESS FULL big_table

1. What does the BUFFER SORT accomplish? Nothing needs to be compared, so why need a sort?
2. Why is it called a BUFFER SORT, and not SORT (JOIN) as for normal mergejoins? Is it something else?
3. If we need sorts, why then is the first table not sorted?

Regards,

Jaap. Received on Tue Nov 21 2006 - 14:56:09 CST