Other MongoDB hints and tips

Example filter queries for target collections

When configuring subsetting in a MongoDB workspace, you can filter a target collections using either a percentage or a filter query.

For example, a customers collection contains the customer first name, last name, and membership status, as shown in the following sample records:

	"FirstName": "John",
	"LastName": "Smith",
	"Member": true
	"FirstName": "Jane",
	"LastName": "Doe",
	"Member": false

To filter the records to only include members, the filter query would be:


As another example, the following filter query checks whether the eighth character in an object ID called _id is equal to 9.

    $expr: {
        $eq: [
        { $substr: [ { $toString: "$_id" }, 8, 1 ] },

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