Amazon DocumentDBSRE & Consulting Services

# Query cluster members, roles, and status
aws docdb describe-db-clusters \
  --db-cluster-identifier production-docdb-cluster \
  --query "DBClusters[0].DBClusterMembers[*].{Instance:DBInstanceIdentifier,IsWriter:IsClusterWriter,Status:DBClusterParameterGroupStatus}" \
  --output table

# Check replication lag across read replicas via CloudWatch
aws cloudwatch get-metric-data \
  --metric-data-queries '[{"Id":"r1","MetricStat":{"Metric":{"Namespace":"AWS/DocDB","MetricName":"ReplicationLag","Dimensions":[{"Name":"DBInstanceIdentifier","Value":"docdb-replica-01"}]},"Period":60,"Stat":"Maximum"}}]' \
  --start-time $(date -u -v-1H +%Y-%m-%dT%H:%M:%SZ) \
  --end-time $(date -u +%Y-%m-%dT%H:%M:%SZ)

// Connect with readPreference=secondaryPreferred to avoid primary locks
db.currentOp({
  "active": true,
  "secs_running": { "$gt": 2 },
  "ns": { "$ne": "local.oplog.rs" }
}).inprog.forEach(function(op) {
  print("OpID: " + op.opid + " | Secs: " + op.secs_running + " | Query: " + tojson(op.command));
});

// Inspect top 5 slow queries exceeding 100ms
db.system.profile.find({ "millis": { "$gt": 100 } }).sort({ "ts": -1 }).limit(5);