So I'm tinkering with the cassandra OGM backend, looking particularly at @ElementCollection since cassandra has native collection types, use of which would sidestep the current limitations on List's bag semantics at the same time as improving performance. The ORM core we sit on assumes that such collections map to a separate table, that being the Relational Way. So assorted munging of metadata is needed to change that model in the backend... At schema definition time it's necessary to identify which Tables should just pass though to underlying db tables and which should be intercepted and rewritten as embedded collection types in the owning table. (hint: associationKeyMetadata.getAssociationKind() == AssociationKind.EMBEDDED_COLLECTION) Having picked out the ones to embed, it's then necessary to figure out what to embed them into. This is where things get sticky - chaining through to the EntityKeyMetaData's Table should reveal where the collection belongs, but it seems that currently OgmCollectionPersister.targetEntityKeyMetadata initialises that to point to the embedded table, not the owning entity's table. IMO that's a bug, but I may be misinterpreting the intent of that metadata. If it is behaving correctly, then how can the relationship information be discovered? thanks Jonathan. -- Registered in England and Wales under Company Registration No. 03798903 Directors: Michael Cunningham (USA), Matt Parson (USA), Charlie Peters (USA), Michael O'Neill(Ireland)