|[Teneo] Help needed with inherance mapping [message #605285]
||Sat, 05 May 2007 14:59
| Alain Picard
Registered: July 2009
I have a pretty complex ecore model implementing the KDM (Knowledge
Discovery MetaModel) OMG standard. This meta-model is built just like
MOF (ecore) in that every class is actually a subclass of the top class
called element. There are also a ton of relation, as it is based on
entity relation. There are also a number of abstract classes in the
model and deep classes hierarchies.
When I use the single_table (default), the database creation fails since
MySql doesn't support more than 64 indexes. The number of tables is
about 30 if I recall correctly.
When I use the joined strategy, I get a database with 269 tables and
many tables are essentially empty, being just there to perform join.
This looks like it will not perform well. Also another posting on the
forum mentioned a limit of 61 joined tables, which I am quite sure would
be exceeded here.
Then I tried the table_per_class strategy and this gave me the just
reported error with the FK name length. But it also ended up with still
230 tables in the db (a quick count a model impl classes gives me 168
The documentation also briefly talks about the MappedSuperClass strategy
that could be used.
What are you suggestions and what have been seen to be best suited to
the kind of model that I am dealing with.
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