Referential integrity constraints are not supported in the RLV store.
In the IQ main store, referential constraint enforcement checks that no foreign tables involved in a referential integrity constraint are currently being modified, by taking a write-intent lock on the foreign table for the duration of the transaction. This referential concurrency checking is handled by the global IQ in-memory catalog. However, taking a global write-intent lock for referential-integrity enforcement is not supported for RLV store tables.
Referential integrity relationships on RLV-enabled tables would also require global table locks from RLV transactions that accessed table-level versioned foreign tables.
For these reasons RI constraints are not supported.