1# Latest secondary's lastWriteDate is used normally with read preference tags.
2---
3heartbeatFrequencyMS: 25000  # 25 seconds.
4topology_description:
5  type: ReplicaSetNoPrimary
6  servers:
7  - &1
8    address: a:27017
9    type: RSSecondary
10    avg_rtt_ms: 5
11    lastUpdateTime: 0
12    maxWireVersion: 5
13    lastWrite: {lastWriteDate: {$numberLong: "125002"}}
14    tags:
15      data_center: tokyo  # No match, but its lastWriteDate is used in estimate.
16  - &2
17    address: b:27017
18    type: RSSecondary
19    avg_rtt_ms: 5
20    lastUpdateTime: 0
21    maxWireVersion: 5
22    lastWrite: {lastWriteDate: {$numberLong: "2"}}  # 125 sec stale + 25 sec heartbeat <= 150 sec maxStaleness.
23    tags:
24      data_center: nyc
25  - &3
26    address: c:27017
27    type: RSSecondary
28    avg_rtt_ms: 5
29    lastUpdateTime: 0
30    maxWireVersion: 5
31    lastWrite: {lastWriteDate: {$numberLong: "1"}}  # Too stale.
32    tags:
33      data_center: nyc
34  - &4
35    address: d:27017
36    type: RSSecondary
37    avg_rtt_ms: 5
38    lastUpdateTime: 0
39    maxWireVersion: 5
40    lastWrite: {lastWriteDate: {$numberLong: "2"}}
41    tags:
42      data_center: tokyo  # No match.
43read_preference:
44  mode: Secondary
45  maxStalenessSeconds: 150
46  tag_sets:
47  - data_center: nyc
48suitable_servers:
49- *2
50in_latency_window:
51- *2
52