Summary

Support SQL / ternary null semantics as an alternative to the MQL null semantics that are the only option at GA.

Background

The GA release ships with MQL null semantics as the only supported mode, enforced via a required configuration property (com.mongodb.hibernate.semantics.nulls=MQL). MQL semantics differ from SQL in a key way: missing fields and explicit null values are treated identically, and null does not equal null.

Virtually every customer migrating from a relational database will expect SQL-style three-valued logic (NULL != NULL, IS NULL vs IS MISSING distinction). Without it, queries behave differently than developers expect, creating silent correctness bugs that are difficult to diagnose.

Expected Behaviour

When SQL / ternary null semantics are enabled:

• NULL = NULL evaluates to UNKNOWN (not TRUE)
• WHERE x = :param with a null param returns no rows (as per SQL)
• Explicit null and missing field are treated distinctly in predicates

Why This Matters

This is the single most likely source of correctness complaints post-GA from migration customers. It is the unlock for the "drop-in" migration messaging. It was deliberately deferred from GA — not deprioritised permanently.