Seeing TTL related spikes in our data base. event though we are not using any TTL indexingin in our collections and doing bulk delete through external service

[chris (Chris Dellaway)]

Sounds exactly like:

TTL issues in mongo

Hello @Shubham_Shailesh_Doijad The system collection system.sessions that is in the config database has a TTL index, the expireAfterSeconds for that is 1800. If you have no other collections with TTL indexes this could be why. s0 [direct: primary] test> db.getSiblingDB('config').system.sessions.getIndexes() [ { v: 2, key: { _id: 1 }, name: '_id_' }, { v: 2, key: { lastUse: 1 }, name: 'lsidTTLIndex', expireAfterSeconds: 1800 } ] https://www.mongodb.com/docs/manual/refer…

@RIA_Phoniex

the connections spike and write latencies spike in db, and then after 30 minute we always see TTL delete operation being triggered

From this description an impulse of connections and writes and inherintly(or explicily) sessions. Then the sessions are then cleaned per TTL.