Re: JDO comparisons

hi eric!

Eric Samson schrieb:
>
> 2 or 3 RDBMS columns can "look like" a Java Collection if you have
> something like JDO, otherwise it will mostly remain "conceptual".

yes, of course this depends on the usage.

> It seems that you consider SQL as a programming language.

not at all. i was just thinking about the task to find an object or several objects that satisfy a certain criterion that involves members of a collection. when coding an application that accesses relational database tables you would of course use SQL to get your hands at the entries. on the other hand you would have to use JDO QL when you are working with JDO - unless you want to instantiate some (possibly huge) collection and search in memory.

> For me SQL
> is well-suited and has been designed for ad-hoc queries outside
> applications.

i don't have a statistic at hand but my guess is that the sheer number of applications that use regularly SQL inside proves its fitness for in-application usage.

> JDO QL aim is only to simply identify entry points from which you'll
> be able to transparently navigate in pure Java. So in JDO queries are
> less
> JDO QL does not pretend to be an ad-hoc query language.

if you look at it from this point of view you are right. the downside of this is that you must materialize your data in memory which can be a serious drawback.

> Anyway, a JDO implementation is free to optionally support SQL in
> addition to JDO QL support. This is exaclty what LiDO, our product
> does.

hm, sounds like you admit the shortcomings of JDO QL by including SQL support into the product... :-)

regards

        robert

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Robert Klemme
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