[EMAIL PROTECTED] wrote:
Hello,
I'm currently modelling and designing a new database according the following
specifications. The general idea is the ability to store arbitrary objects,
which have attributes of various kinds. The attributes themselves may be
multivalued. The objects being stored need to be versioned, so that there's
a way to go back to previous versions of an object. The objects represent
metadata of media files and the data itself comes from various automated
sources and manual editing by a user.
Michael,
That approach will work OK for the simple types (str, numbers, dates,
bool ) attribute. And also it assumes fairly flat object structures.
How are you going to deal with the attribute which is some kind of
Collection as you mentioned multivalue, or worth if your attribute
points to another object ? You can represent collection as String and
later parse them, but I think it kind of defeats the purpose.
You can also serialize your object as XML and store those serializations
as strings or Blobs.
All in all the SQL only databases are not very good dealing with OO
data. You either store fairly simple Objects into the DB or spend a lot
of time on Mapping OO to SQL -- by time I mean a development time to
design and implement those mapping and then runtime penalty to assemble
and disassemble your object structures for your application to and from DB.
For that you may need to take a look at some Object- relational
extensions of the databases -- Oracle has it, PostgreSQL does have
extensions. Or you may need to use pure OO DB or XML databases.
Just My 2c.
My current idea was the following:
- CREATE TABLE objects (id TEXT, version TEXT)
- CREATE TABLE attributes (object_id TEXT, version TEXT, name TEXT, order
INT, type INT, value TEXT)
Is there anyone who has experience with this kind of design, do you have
better ideas on modelling this kind of data?
Thanks,
Mike
-- Mark Pirogovsky
"Computers made it possible to make millions mistakes a second"
"Ask no questions and hear no lies"
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