Re: Object Oriented Wrapper classes to SQL statements

David Cressey wrote:
>
> Clifford,
> Or maybe I shouldn't be surprised.

I've never seen Rdb, but there aren't many logical choices for such a syntax. It has to be prefix-notation and you can put the function-name outside or inside the brackets (vis C/Pascal/etc style vs Lisp style).

I hope it's now clear to Rachel what objects she must create... Any program that must do algebraic manipulation creates an object class for each operator type, whether using an O-O language or not.

> That output is after the optimizer has done reworking the plan,
> and decided on the cheapest path. That, in turn can be used to
> tune the query, or to provide hints.

I love the graphical output of Microsoft SQL Server's Query analyser. You can float the mouse over any node or any connection and see the statistics and cost estimates for that item. The optimiser itself has some weaknesses (LIKE throws it *right* off!), though generally it's been fine.

> BTW, Rdb had (still has) a really great optimizer.

Until the mid-80's, almost no-one was using cost-based optimisers, they were all using heuristics - amazing! Once one starts doing actual cost estimates and gathering enough statistics to support them, it's great how often you can come up with the actual best plan - some of the chosen best query plans are surprisingly different from what a human would even be likely to think of...

--
Clifford Heath, ManageSoft Corporation