Add subscription information to mosquitto_db_dump

[gw1urf]

I sometimes need to use mosquitto_db_dump --client-stats to debug why the database has grown large. Usually it's because a client with a persistent subscription has gone away, never to come back. In that case, I need to know the topic information so I can unsubscribe from it.

At present mosquitto_db_dump shows the number of subscriptions, but not their topics. Please find attached a patch which adds that information to the --client-stats output.

Here's some example output with the patch applied:

# mosquitto_db_dump --client-stats mosquitto.db 
SC: 0 SS: 0 MC: 0 MS: 0   client_id_1
SC: 6 SS: 491 MC: 10 MS: 3493   client_id_2 (dhcp/#, healthcheck/#, 433/db, 433/#, hive/json, webcam/weather)
SC: 3 SS: 269 MC: 0 MS: 0   client_id_3 (webcam/front/#, webcam/front/01/0/0/2/1/#, webcam/front/01/#)

db_dump.patch.txt

[ralight]

That sounds reasonable to me.

[bahientn9x]

I sometimes need to use mosquitto_db_dump --client-stats to debug why the database has grown large. Usually it's because a client with a persistent subscription has gone away, never to come back. In that case, I need to know the topic information so I can unsubscribe from it. At present mosquitto_db_dump shows the number of subscriptions, but not their topics. Please find attached a patch which adds that information to the --client-stats output. Here's some example output with the patch applied:

# mosquitto_db_dump --client-stats mosquitto.db 
SC: 0 SS: 0 MC: 0 MS: 0   client_id_1
SC: 6 SS: 491 MC: 10 MS: 3493   client_id_2 (dhcp/#, healthcheck/#, 433/db, 433/#, hive/json, webcam/weather)
SC: 3 SS: 269 MC: 0 MS: 0   client_id_3 (webcam/front/#, webcam/front/01/0/0/2/1/#, webcam/front/01/#)

db_dump.patch.txt

how to use the command "mosquitto_db_dump".I have an error that I cannot find the command mosquitto_db_dump. My mosquitto version 1.4.5

[ralight]

@bahientn9x If you're compiling by yourself, it's in the apps/db_dump directory. It's not something that is typically provided in binary installations though.

[jsaak]

You can connect to the server with mosquitto_sub with clean_session true, and with the same client_id, and the subscriptions will all be removed.