Import Filtered Data from MongoDB

This example shows how to import flight data from a MongoDB^® collection into the MATLAB^® workspace using the Database Toolbox™ interface for MongoDB. The example then shows how to use a MongoDB query with filter criteria and a field list, and how to perform a simple data analysis based on the filtered flight data.

To run this example, you must first install the Database Toolbox interface for MongoDB. For details, see Database Toolbox Interface for MongoDB Installation.

Create a MongoDB connection to the database mongotest. Here, the database server dbtb01 hosts this database using port number 27017.

server = "dbtb01";
port = 27017;
dbname = "mongotest";
conn = mongo(server,port,dbname)

conn = 

  mongo with properties:

               Database: 'mongotest'
               UserName: ''
                 Server: {'dbtb01'}
                   Port: 27017
        CollectionNames: {'airlinesmall', 'employee', 'largedata' ... and 3 more}
         TotalDocuments: 23485919

conn is the mongo object that contains the MongoDB connection. The object properties contain information about the connection and the database.

• The database name is mongotest.

• The user name is blank.

• The database server is dbtb01.

• The port number is 27017.

• This database contains six document collections. The first three collection names are airlinesmall, employee, and largedata.

• This database contains 23,485,919 documents.

Verify the MongoDB connection.

isopen(conn)

ans =

  logical

   1

The database connection is successful because the isopen function returns 1. Otherwise, the database connection is closed.

Specify the airlinesmall collection. Define the MongoDB query to filter the flight data for the years 1998 through 1999. Specify fields to retrieve from the collection.

collection = "airlinesmall";
mongoquery = '{"Year":{$gte:1998,$lt:2000}}';
fields = ['{"Year":1.0,"Month":1.0,"DayofMonth":1.0,"DayOfWeek":1.0,' ...
    '"DepTime":1.0,"ArrTime":1.0}'];

Retrieve flight data using the MongoDB connection. documents is a structure array with fields that correspond to the specified fields.

documents = find(conn,collection,'Query',mongoquery,'Projection',fields)

documents = 

  10911×1 struct array with fields:

    x_id
    Year
    Month
    DayofMonth
    DayOfWeek
    DepTime
    ArrTime

Determine the unique years in the data.

years = [documents(:).Year];
unique(years)

ans =

        1998        1999

Close the MongoDB connection.

close(conn)