{"id":7770,"date":"2020-07-30T22:04:49","date_gmt":"2020-07-31T05:04:49","guid":{"rendered":"https:\/\/www.couchbase.com\/blog\/?p=7770"},"modified":"2025-06-13T21:01:56","modified_gmt":"2025-06-14T04:01:56","slug":"migrating-from-mongodb-to-couchbase-part-2","status":"publish","type":"post","link":"https:\/\/www.couchbase.com\/blog\/migrating-from-mongodb-to-couchbase-part-2\/","title":{"rendered":"Migrating Data from MongoDB to Couchbase, Part 2"},"content":{"rendered":"

Prolog<\/h2>\n

The previous article<\/a> provided details on how to migrate a MongoDB data set to Couchbase Server. This article shows you how to use the Couchbase SDK to access the data via a Java console application. Code snippets show how to connect to the Couchbase cluster, perform key\/value operations, and execute secondary lookups via N1QL queries side-by-side with corresponding code to do the same with the Mongo Java SDK.<\/p>\n

All code from this blog is available in the following Git repository: mongodb-to-couchbase<\/a>.<\/p>\n

Prerequisites<\/h2>\n

A Couchbase cluster containing the data set as per the details in the previous article<\/a>.<\/p>\n

Create an Application User<\/h2>\n

Before a client (application) can connect to the Couchbase Server cluster you need to define an application user that is used for authentication by the client. Couchbase Role-Based Access Control<\/a> allows you to define users and assign appropriate roles to them. Use the web console to create an application user named mflix_client<\/strong> as follows.<\/p>\n

Go to the Security<\/strong> section in the web console and click ADD USER<\/strong>:<\/p>\n

\"\"<\/p>\n

Configure the mflix_client<\/strong> user as follows and click Add User<\/strong>:<\/p>\n

    \n
  1. Username<\/strong>: mflix_client<\/li>\n
  2. Password<\/strong>: password (or any password of your choosing).<\/li>\n
  3. Verify Password<\/strong>: same as Password<\/strong> value above.<\/li>\n
  4. Roles<\/strong>: Expand the sample_mflix<\/strong> section and select Application Access<\/strong>. Users with the Application Access role<\/a> have full read and write access to all data in the sample_mflix bucket. The role does not allow access to the Couchbase Web Console: it is intended for applications, rather than users.<\/li>\n<\/ol>\n

    \"\"<\/p>\n

    In the Security<\/strong> section you will see the new mflix_client user:<\/p>\n

    \"\"<\/p>\n

    Create Indexes for N1QL Queries<\/h2>\n

    Secondary Indexes<\/a> in Couchbase Server support the efficient execution of queries (or secondary lookups) just like indexes in MongoDB. Code samples in this article execute N1QL queries<\/a> that use two indexes you will create by executing N1QL queries. Go to the Query<\/strong> section in the web console:<\/p>\n

    \"\"<\/p>\n

    The first index is on the name attribute of all comment documents in the sample_mflix bucket. Enter the following N1QL statement in the Query Editor:<\/strong><\/p>\n

    CREATE INDEX idx1 on sample_mflix(name) WHERE type=\"comment\"<\/pre>\n
    \"\"<\/p>\n
    Click Execute<\/strong> and after a few moments the index creation<\/a> is complete:<\/p>\n
    \"\"<\/p>\n
    The second index is on the year, imdb.rating, & title attributes of all movie documents in the sample_mflix bucket. Enter the following N1QL statement in the Query Editor<\/strong>:<\/p>\n
    CREATE INDEX idx2 on sample_mflix(year, imdb.rating, title) WHERE type=\"movie\"<\/pre>\n
    \"\"<\/p>\n
    Click Execute<\/strong> and after a few moments the index creation is complete:<\/p>\n
    \"\"<\/p>\n
    Go to the Indexes<\/strong> section in the web console to verify that indexes idx1<\/strong> & idx2<\/strong> exist:<\/p>\n
    \"\"<\/p>\n
    Convert MongoDB API calls to Couchbase API calls<\/h2>\n
    The sample code for this article uses the Couchbase & MongoDB Java SDKs and is provided only as an example of how to use some of the SDK APIs. Refer to the following links for the full Couchbase SDK documentation for your language:<\/p>\n