Database / MongoDB Interview questions

What is the structure of ObjectID in MongoDB?

ObjectId is 12 bytes: 4-byte timestamp, 5-byte random value, and 3-byte incrementing counter. The timestamp makes default _id values roughly sortable.

ObjectID is a 12-byte BSON type. It is composed of,

4 bytes value representing seconds,
3 byte machine identifier,
2 byte process id,
3 byte counter.

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