# Attempt to select the secondary, except its tag doesn't match. # Fall back to primary. --- topology_description: type: ReplicaSetWithPrimary servers: - &1 address: a:27017 avg_rtt_ms: 5 type: RSPrimary tags: data_center: nyc - &2 address: b:27017 avg_rtt_ms: 5 type: RSSecondary tags: data_center: sf # No match. operation: read read_preference: mode: SecondaryPreferred tag_sets: - data_center: nyc suitable_servers: - *1 in_latency_window: - *1