Andy Jefferson

1-1 uni join table works fine. This issue should be for 1-1 BI JOIN TABLE relation.

No. That is dependent on contributions, this being open source and all. As per the "unresourced" tag on this issue

Thx for your input, interesting to hear. A comparison of the 3 "bulk"/"batch" options (EXISTS, IN, JOIN) for EclipseLink JPA is present on this link https://java-persistence-performance.blogspot.co.uk/2010/08/batch-fetching-optimizing-object-graph.html

"Join groups" are not supported at all.

See ObjectExpression.cast(). Near the end there is a block "if (castSqlTbl == table)". We need to allow ObjectExpression to have a BooleanExpression adding (when part of FILTER), and then when...

An RDBMS "VIEW" doesn't have a primary key in most treatments of VIEW.

Sample test that shows a simple field persisted as CLOB (passes), Collection field persisted (serialised) as BLOB (passes), and Collection field persisted into JOIN table with CLOB element (fails). [test.zip](https://github.com/datanucleus/datanucleus-rdbms/files/6118171/test.zip)

Anybody can get the code and contribute such things. We already provide 2 such mapping strategies, multiple FKs, or single String which includes the class + id.

Note that this is strongly linked to an update to the enhancement contract in https://github.com/datanucleus/datanucleus-core/issues/155

This is included as part of https://github.com/locationtech/jts/issues/439. Suggest that you close this one