Unsupported operators

Status: Not supported. These have no native matcher at all — a query containing one falls back to Flink entirely, per the all-or-nothing island rule.

Operator	SQL surface	Why
Correlate (most shapes)	Lateral table functions; UNNEST with a pushed condition the expression engine can't encode, or any condition over a LEFT UNNEST	No native path yet. Exception: plain INNER or LEFT UNNEST of a single ARRAY/MAP/MULTISET column (optionally WITH ORDINALITY, INNER including a pushed element filter) is native — see Unnest / Correlate.
Match	MATCH_RECOGNIZE (CEP / row-pattern matching)	No native path; MATCH_ROWTIME and MATCH_PROCTIME require this operator and fall back with it.
GroupWindowTableAggregate	A TableAggregateFunction inside a legacy group window	No native path. Ordinary legacy TUMBLE/HOP aggregates and event-time SESSION are native — see Window aggregate.
IncrementalGroupAggregate	The five-node chain a distinct aggregate plans to only when table.optimizer.distinct-agg.split.enabled is on (partial local → incremental → final global over a bucket key)	Deliberate non-goal: the knob mitigates state-backend hot-key skew that an in-process distinct set doesn't exhibit. The default mini-batch plan for distinct aggregates — LocalGroupAggregate + GlobalGroupAggregate with a distinct MapView partial — is native; see GROUP BY.
GroupTableAggregate	TableAggregateFunction	No native path.
DropUpdateBefore, Values	Misc	No native path. (A non-temporal Sort is parity, not a gap — Flink itself rejects it in streaming.)
DeltaJoin	A join Flink rewrites into a delta join under table.optimizer.delta-join.strategy	No native path. A block containing a delta join is not rejected by the FORCE guard, but ordinary admission and island checks still apply; DeltaJoin remains unsupported. Under FORCE, a block containing an ordinary join and no delta join is left unchanged so Flink can perform its statement-wide validation — see Global switches.
LegacyTableSourceScan, LegacySink	Legacy (pre-DynamicTableSource/Sink) connectors	No native path.
Python* (PythonCalc, PythonCorrelate, PythonGroupAggregate, PythonOverAggregate, …)	PyFlink UDFs	No native path — a Python UDF can't run inside a native island.

Pattern matching, including MATCH_ROWTIME and MATCH_PROCTIME, is tracked in issue #78.