Oracle - what sort of database system is it? Is it for Unix?

[Mike Olson]

In article <1991Jan29.152745.9028 at cs.odu.edu> aiko at cs.odu.edu (John K Hayes)
asks regarding oracle:

> Does it run on VAX VMS?  
> Can someone describe generally what Oracle is?

i know that early versions of oracle did not include a query optimizer.
qualifications were evaluated left-to-right in the user's query.  this
led to some predictable problems:  the user was not insulated from changes
in data representation, and had to expend a fair amount of energy in
optimizing queries by hand by ordering qual clauses cleverly.

do later releases of oracle include a query optimizer?  at what release
level was one added?  and what (roughly) is the cost function used to
pick a plan?  the last question is intended to discover whether oracle's
query optimizer is less than, equal to, or greater than the standard
optimizer that was designed for system r in the 1970's.

any oracle implementors out there?
					mike olson
					postgres research group
					uc berkeley
					mao at postgres.berkeley.edu