Loop through all MongoDB collections and execute query?

First of all, you need to get your collection with the help of getCollectionNames().

The database name is “test”. Let us loop through all MongoDB collections and execute the query. The query is as follows −

> db.getCollectionNames().forEach(function(collectioNameDemo)
... {
   ... var nextDemo = db[(collectioNameDemo) ].find().sort({_id:-1}).limit(1);
   ... if (nextDemo.hasNext())
   ... {
      ... printjson(nextDemo.next()._id.getTimestamp());
   ... }
... });

The following is the output −

ISODate("2019-02-21T18:52:43Z")
ISODate("2019-03-19T17:49:00Z")
ISODate("2019-03-06T15:40:12Z")
ISODate("2019-03-15T16:31:50Z")
ISODate("2019-02-21T15:40:52Z")
ISODate("2019-03-06T06:14:37Z")
ISODate("2019-02-21T19:29:15Z")
ISODate("2019-03-15T13:35:33Z")
ISODate("2019-03-14T21:13:58Z")
ISODate("2019-03-18T22:02:54Z")
ISODate("2019-03-22T18:01:45Z")
ISODate("2019-03-06T16:21:14Z")
ISODate("2019-02-20T15:04:32Z")
ISODate("2019-03-06T07:45:42Z")
ISODate("2019-03-19T12:33:17Z")
ISODate("2019-03-20T21:39:21Z")
ISODate("2019-03-15T16:44:26Z")
ISODate("2019-03-22T06:20:45Z")
ISODate("2019-02-21T16:40:55Z")
ISODate("2019-02-21T12:45:20Z")
ISODate("2019-03-06T16:05:48Z")
ISODate("2019-03-06T16:00:08Z")
ISODate("2019-02-28T12:43:56Z")
ISODate("2019-03-20T22:11:41Z")
ISODate("2019-03-06T05:56:45Z")
ISODate("2019-03-06T07:34:12Z")
ISODate("2019-03-14T21:00:16Z")
ISODate("2019-02-28T10:33:39Z")
ISODate("2019-03-06T05:11:10Z")
ISODate("2019-02-28T09:44:28Z")
ISODate("2019-03-06T10:13:22Z")
ISODate("2019-03-17T21:35:26Z")