Is MongoDB _id (ObjectId) generated in an ascending order?

Question

I know how the _id column contains a representation of timestamp when the document has been inserted into the collection. here is an online utility to convert it to timestam

Answer 1

For mongo version >= 3.4, the Objectid generation is changed a little. Its structs are:

• a 4-byte value representing the seconds since the Unix epoch,
• a 5-byte random value, and
• a 3-byte counter, starting with a random value.

So the first 4 bytes are still the seconds since the Unix epoch, it is still almost ascending but not strictly.

https://docs.mongodb.com/manual/reference/bson-types/#objectid