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Object oriented databases.

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Prevalent Objects

IIUC, prevalent objects (and Prevayler) is a database of objects in RAM.

Prevayler doesn't map data into an RDBMS. Prevayler removes the RDBMS entirely.

In Prevayler, your "database" is represented natively as a collection of objects, which reference each other by holding pointers to each other, just like any other God-fearing object in core memory. It builds indices, also in memory, to support query operations on this big collection of objects. The whole shebang is periodically serialized to disk, to make it persistent between invocations of your application.

So: Prevayler is natively an OODBMS, and not a tool to map between OO and relational databases. Any language that supports introspection can support prevalence, and hence Prevayler. Such languages include Perl, Python and C#.

Even for languages that don't support introspection, you could still implement a prevalence system, but it would be rather awkward and not seamless. Your objects would all need to know how to serialize and deserialize themselves, and also provide indexing information about themselves...a clunky and unwiedly approach. Which is why you're unlikely to see Prevayler for C++ any time soon.

I disagree with Prevayler's approach for more fundamental reasons, having to do with the fact that the whole database must always exist in memory. But I won't get into that here.

Re:Why Java? (Score:3) by MSBob (307239) on Tuesday September 23, @08:36PM (#7039356)

How do you effectively query that thing? OO links are not efficient to follow unless you set up hashmaps all over the place which would make your object model absolutely horrible to maintain...

Re:Why Java? (Score:2) by jafac (1449) on Tuesday September 23, @09:11PM (#7039628) ( http://slashdot.org/ )

I disagree with Prevayler's approach to "replacing" RDBMS' for the simple fact that it fails the ACID test.

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  • () RandyKramer - 06 Oct 2003
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Topic revision: r1 - 2003-10-06 - RandyKramer
 
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