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From "Jukka Zitting" <jukka.zitt...@gmail.com>
Subject Re: Query Performance and Optimization
Date Thu, 08 Mar 2007 07:32:52 GMT
Hi,

On 3/8/07, Michael Neale <michael.neale@gmail.com> wrote:
> On 3/7/07, Stefan Guggisberg <stefan.guggisberg@gmail.com> wrote:
> > On 3/7/07, Michael Neale <michael.neale@gmail.com> wrote:
> > > The DDL generation kind of scares me, in terms of complexity, but I
> > > think its necessary to let RDBMS "do its thing" so to speak?
> >
> > why?
>
> Mainly for queries. if we have a  node type def that has something:title,
> something:size etc... then if they map to  columns in a table called
> something_title, something_age we can get the RDBMS to do indexing.

Note that the hierarchical content model of JCR is fundamentally
different from the relational model. There is no way you could achieve
such a mapping without major compromizes especially with residual item
definitions but also with things like type inheritance and even
handling of the tree structure.

> However, this is turning jackrabbit into a kind of ORM itself - probably
> not one of the aims ;)

Exactly. There are already a number of mature ORM tools out there,
each with the fundamental limitations of the ORM approach. Jackrabbit
is actually breaking those barriers by offering an alternative storage
model and imposing the relational model on Jackrabbit would IMHO be a
major step backwards.

In fact I think the use of relational databases in the current
database persistence managers and the incoming bundle persistence
managers is a necessary evil until we come up with a "native"
persistence model that achieves the required ACID features without the
need for an external component to "do its thing". :-)

BR,

Jukka Zitting

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