The sink-connector-client
executable or the storage database created by sink connector can be used to monitor the replication lag.
sink-connector-client
The sink-connector-client show_replica_status
command prints two values that can be used for monitoring.
Seconds_Behind_Source
can be monitored and alerted if it exceeds a threshold value.
Replica_Running
can also be monitored to check if the replication was stopped.
bash-4.4# ./sink-connector-client show_replica_status
[
{
"Seconds_Behind_Source": 18000
},
{
"Replica_Running": false
},
{
"Database": "test"
},
{
"record_insert_ts": 2024-03-28T12,
"offset_key": "[\"company-1\",{\"server\":\"embeddedconnector\"}]",
"record_insert_seq": 186,
"id": "9cae16ad-f938-480c-b833-07f6f7c02f36",
"offset_val": "{\"transaction_id\":null,\"ts_sec\":1711645477,\"file\":\"mysql-bin.000003\",\"pos\":276,\"gtids\":\"cbba0506-ed24-11ee-8921-0242ac180005:1-56\",\"row\":1,\"server_id\":604,\"event\":2}"
}
]
Query
Querying the storage database directly to get the seconds_behind_source
column value.
Alerts can be setup on this column(seconds_behind_source
) if this exceeds a threshold value
SELECT
now() - fromUnixTimestamp(JSONExtractUInt(offset_val, 'ts_sec')) AS
seconds_behind_source,
toDateTime(fromUnixTimestamp(JSONExtractUInt(offset_val,
'ts_sec')), 'UTC') AS utc_time,
fromUnixTimestamp(JSONExtractUInt(offset_val, 'ts_sec')) AS
local_time,
*
FROM altinity_sink_connector.replica_source_info
FINAL
Query id: 061bedc0-f587-49a3-96fa-acb55d6f28f5
Row 1:
seconds_behind_source: 2
utc_time:
2024-03-28 06:11:15
local_time:
2024-03-28 01:11:15
id:
3513a07a-7d88-40d9-895c-5bb2aee80984
offset_key:
["company-1",{"server":"embeddedconnector"}]
offset_val:
{"transaction_id":null,"ts_sec":1711606275,"
file":"binary.126436","pos":765189094,"row":27,"server_id":142,"event":
280}
record_insert_ts:
2024-03-28 01:11:16
record_insert_seq:
6570
Query to monitor INSERT duration in ClickHouse
select event_time, written_rows from system.query_log where event_time > now () - interval 60 minute and type='QueryFinish' and query like 'insert into table(%'
Query to monitor Part log in ClickHouse
select event_time, database, table, rows, duration_ms,size_in_bytes from system.part_log where table='table' and event_type='NewPart' and event_time > now () - interval 30 minute and database='db' ;
JMX metrics of sink connector are exposed through the port
The JMX_exporter docker image scrapes the JMX metrics from the sink connector The metrics can be read through the following URL http://localhost:9072/metrics
A Grafana dashboard is included to view JMX metrics.
The docker-compose launches Grafana application which can be accessed in http://localhost:3000
The default username/password is admin/admin
Memory
Sink Connector Config OpenJDK 11.0.14.1
-Xms256M, -Xmx2G,
Throughput
Increase the fetch.min.bytes
property to increase the size of message
consumed
[1] https://strimzi.io/blog/2021/01/07/consumer-tuning/