Grabs AG latency information. Run on primary to get information for all replicas and all databases, run on a secondary to get information for just that server. *note: MintoRedo is approximate based on the size of the queue and rates, this fluctuates so it not always accurate

GetAGLatency.sql

SELECT DB_NAME(database_id),
       a.replica_server_name,
       database_id AS di,
       last_redone_time,
       DATEDIFF(MINUTE, last_sent_time, last_received_time) AS ReceiveLatencyS,
       DATEDIFF(SECOND, last_sent_time, last_redone_time) AS RedoLatencyS,
       CASE
           WHEN redo_queue_size = 0 THEN
               0
           WHEN redo_rate = 0 THEN
               0
           ELSE
               CAST(redo_queue_size / (redo_rate * 1.0) AS NUMERIC(12, 3))
       END AS MinToRedo,
       CASE
           WHEN log_send_queue_size = 0 THEN
               0
           WHEN log_send_rate = 0 THEN
               0
           ELSE
               CAST(log_send_queue_size / (log_send_rate * 1.0) AS NUMERIC(12, 3))
       END AS SecToLogSend,
       log_send_queue_size AS SendQueue,
       log_send_rate,
       redo_queue_size,
       redo_rate,
       synchronization_state_desc,
       synchronization_health_desc,
       database_state_desc,
       is_suspended,
       suspend_reason_desc,
       last_sent_time,
       last_received_time,
       last_hardened_time,
       last_redone_time,
       end_of_log_lsn,
       last_commit_lsn,
       last_commit_time
FROM sys.dm_hadr_database_replica_states d
    JOIN sys.availability_replicas a
        ON d.replica_id = a.replica_id
WHERE d.last_redone_time IS NOT NULL;