fix: Skip disconnected correlated-only query graphs#701
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…MATCH When a comma-separated pattern in OPTIONAL MATCH references an already-bound variable without adding new constraints (e.g., bare (n3) in OPTIONAL MATCH), the binder creates a disconnected query graph. This graph was planned as a full node-table scan, producing extra rows that doubled the cardinality. Fix: in planQueryGraphCollection, skip query graphs that have no relationships and whose nodes are all correlated (already bound in the outer plan). Their correlated expressions are already captured via join conditions. Fixes #697.
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When a comma-separated pattern in OPTIONAL MATCH references an already-bound variable without adding new constraints (e.g., bare (n3) in OPTIONAL MATCH), the binder creates a disconnected query graph. This graph was planned as a full node-table scan, producing extra rows that doubled the cardinality.
Fix: in planQueryGraphCollection, skip query graphs that have no relationships and whose nodes are all correlated (already bound in the outer plan). Their correlated expressions are already captured via join conditions.
Fixes #697.