Re: The Myth of relational algebra (was Re: Clean Object Class Design -- What is it?)
Date: Fri, 07 Sep 2001 16:33:06 GMT
In article <9na529$6u5$1_at_wrath.news.nacamar.de>, Adrian Veith says...
>6. Not shown but obvious: Queries are much easier to formulate in an OODB,
>than in a RDBMS
Thre is a famous example for you to crack: find all managers who earn more than sum of their employees.
>Another myth states, that RDBMS are much more effective and quicker than an
>OODB. Often this myth is explained with relational algebra and the
>possibility to optimize queries in an RDBMS.
>As with all myths, there is true part:
>Relational algebra gives you the possibility to transform a query in order
>to optimize it.
>1. That all optimizations of a query are done with relational algebra. The
>most common optimization is to use an index. Relational algebra is used to
>transform the query to use the index. But the index in itself is not defined
>by relational algebra. (Since an index is normally a tree-structure, it has
>more in common with an OODB if you want)
Not quite: materialized views work much the same way as indexes with query rewrite. They allow to speed up complex queries with joins and aggregates. How can you leverage materialized view technique in OODB without relational closure? Received on Fri Sep 07 2001 - 18:33:06 CEST