Just thinking that a relational db with an ORM is in many ways very similar to an object oriented database. My experience lies solely with RDMS with a hint of ORM, so it seems to me that object oriented databases are very similar but without the experience I can't say for sure.
If you have used object oriented databases and ORMs can you compare them? What are the weak points associcated with object oriented databases compared to RBMS+ORM?
What are the weak points associated with object oriented databases compared to RBMS+ORM?
The biggest weakness is the lack of standardization: no standard API, no standard query language (the OQL attempt has been a big failure) and thus the lack of portability and interoperable tools (for backup, archiving, migration, etc). You don't want that when it comes to data.
This explains IMO why OODBMS are a failure from an adoption point of view and why RDBMS will stay around for a while, regardless of the NoSQL movement (I have the feeling that OODBMS vendors see the NoSQL movement as an opportunity for a come back after some rebranding of their products).
Chris Date agrees:
... 'object/relational' system would be nothing more nor less than a true relational system ... A proper object/relational system is just a relational system with proper type support ... which just means it's a proper relational system, no more and no less.
SQL and Relational Theory: How to Write Accurate SQL Code, p 36