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A Query sorts and filters the data at a Database location so only a subset of the child data is included. This can be used to order a collection of data by some attribute (for example, height of dinosaurs) as well as to restrict a large list of items (for example, chat messages) down to a number suitable for synchronizing to the client. Queries are created by chaining together one or more of the filter methods defined here.

Just as with a Reference, you can receive data from a Query by using the on() method. You will only receive events and DataSnapshots for the subset of the data that matches your query.

Read our documentation on Sorting and filtering data for more information.