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The DATE type in MongoDB can store date and time values as a combined unit. The BSON Date type is a signed 64-bit integer representing the number of milliseconds since the Unix epoch (Jan 1, 1970).
MongoDB has a Date BSON type that allows you to store dates as dates. You can also store dates as strings, if that's what you need. Taking it a step further, you can also convert a Date to a string.
Timestamps. BSON has a special timestamp type for internal MongoDB use and is not associated with the regular Date type. This internal timestamp type is a 64 bit value where: the most significant 32 bits are a time_t value (seconds since the Unix epoch)
MongoDB stores times in UTC by default, and will convert any local time representations into this form. Applications that must operate or report on some unmodified local time value may store the time zone alongside the UTC timestamp, and compute the original local time in their application logic.
The best way is to store native JavaScript Date objects, which map onto BSON native Date objects.
> db.test.insert({date: ISODate()})
> db.test.insert({date: new Date()})
> db.test.find()
{ "_id" : ObjectId("..."), "date" : ISODate("2014-02-10T10:50:42.389Z") }
{ "_id" : ObjectId("..."), "date" : ISODate("2014-02-10T10:50:57.240Z") }
The native type supports a whole range of useful methods out of the box, which you can use in your map-reduce jobs, for example.
If you need to, you can easily convert Date objects to and from Unix timestamps1), using the getTime() method and Date(milliseconds) constructor, respectively.
1) Strictly speaking, the Unix timestamp is measured in seconds. The JavaScript Date object measures in milliseconds since the Unix epoch.
So if the insert time is what you need, it's already there:
Login to mongodb shell
ubuntu@ip-10-0-1-223:~$ mongo 10.0.1.223
MongoDB shell version: 2.4.9
connecting to: 10.0.1.223/test
Create your database by inserting items
> db.penguins.insert({"penguin": "skipper"})
> db.penguins.insert({"penguin": "kowalski"})
>
Lets make that database the one we are on now
> use penguins
switched to db penguins
Get the rows back:
> db.penguins.find()
{ "_id" : ObjectId("5498da1bf83a61f58ef6c6d5"), "penguin" : "skipper" }
{ "_id" : ObjectId("5498da28f83a61f58ef6c6d6"), "penguin" : "kowalski" }
Get each row in yyyy-MM-dd HH:mm:ss format:
> db.penguins.find().forEach(function (doc){ d = doc._id.getTimestamp(); print(d.getFullYear()+"-"+(d.getMonth()+1)+"-"+d.getDate() + " " + d.getHours() + ":" + d.getMinutes() + ":" + d.getSeconds()) })
2014-12-23 3:4:41
2014-12-23 3:4:53
If that last one-liner confuses you I have a walkthrough on how that works here: https://stackoverflow.com/a/27613766/445131
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