How to get per collection last insert/update/delete time

[Sarthak]

Hi,
I have a need to see the timestamp of the last insert/update/delete
was executed on a given collection. Is there a utility method to see
this information?

I have tried .stats() but it does not give this information

[Bernie Hackett]

You could get the last insert time by doing something like:

db.<collection>.find().sort({'_id': -1}).limit(1)

and then calling getTimestamp() on the ObjectId (assuming you are
using ObjectIds).

There isn't a good way to see last update/delete time. If you are
using replica sets you could get that from the oplog.

[Sarthak]

Hi Bernie,

Thats a good workaround.. however, we have our own unique values as
_id to maintain uniqueness. So I dont have a way to do what you said.
Even my id keys is a complex hash that does not follow any particular
order.

Are there any disadvantages of doing this? Will the reads/writes
performance deteriorate as opposed to using _id? I believe there are
other ways to make sure that some field's value is unique across a
collection

[Bernie Hackett]

If your dataset is small enough that your _id_ index is entirely in
memory there shouldn't be any problems. If the dataset is large there
**could** be an impact to the performance of inserts and queries
**if** your _id is random and not increasing.