Hi,
One of optimizer overrides, that a user can specify, is joinStrategy. The functional spec for joinStrategy says following "The joinStrategy property can be used only within a TableExpression, but it must be used in conjunction with the joinOrder property. Do not let the optimizer choose the join order.
"
When I wrote the functional spec, I got this piece of information from old Cloudscape release documentation, where the optimizer overrides were available in a non-portable syntax. I also got some of the test cases from that old Cloudscape release and one of the test cases is as follows
SELECT * FROM t1 a, t1 b --DERBY-PROPERTIES joinStrategy=nestedloop
WHERE a.c1=b.c1
WHERE a.c1=b.c1
As you can see, the example above doesn't specify joinOrder override along with joinStrategy. Should Derby (in its code) make it mandatory that joinStrategy can't be specified w/o joinOrder? If not, then should the functional spec be changed? What happens if user doesn't specify joinOrder along with joinStrategy? Will joinStrategy be ignored. I haven't had a chance to investigate this yet. I only stumbled on it last night when I was reviewing Eric's hardwork on getting this feature documented and noticed that the example for joinStrategy didn't include joinOrder.
thanks,
Mamta
