Migrating Data Using mongoexport and mongoimport

Precautions

• The mongoexport and mongoimport tools support only full migration. To ensure data consistency, stop services on the source database and stop writing data to the source database before the migration.
• You are advised to perform the migration during off-peak hours to avoid impacting services.
• The admin and local system databases cannot be migrated.
• Make sure that no service set has been created in the system databases admin and local in the source database. If there is already a service set, migrate them out of the system databases admin and local before migration.
• Before importing data, ensure that the necessary indexes are there on the source database. Delete any unnecessary indexes and create any necessary indexes before migration.
• If you choose to migrate a sharded cluster, you must create a set of shards in the destination database and configure sharding. In addition, indexes must be created before migration.

Prerequisites

1. An ECS or a device that can access DDS is ready for use.
   • To connect to a DDS DB instance through a private network from an ECS, create and log in to the ECS. For details, see Purchasing an ECS and Logging In to an ECS.
   • To bind an EIP to a DB instance:
     1. Bind an EIP to a node in the instance. For details about how to bind an EIP to a node, see "Binding an EIP" in Getting Started with Document Database Service.
     2. Ensure that your local device can access the EIP that has been bound to the DB instance.
2. A migration tool has been installed on the prepared ECS.

   For details on how to install the migration tool, see How Can I Install a MongoDB Client?

   

   The MongoDB client provides the mongoexport and mongoimport tools.

Exporting Data

1. Log in to the ECS or the device that can access DDS.
2. Use the mongoexport tool to transfer data from the source database to a .json file.

   The SSL connection is used as an example. If you select a common connection, delete --ssl --sslAllowInvalidCertificates from the following command.

   ./mongoexport --host <DB_ADDRESS> --port <DB_PORT> --ssl --sslAllowInvalidCertificates --type json --authenticationDatabase <AUTH_DB> -u <DB_USER> --db <DB_NAME> --collection <DB_COLLECTION> --out <DB_PATH>

   • DB_ADDRESS is the database address.
   • DB_PORT is the database port.
   • AUTH_DB is the database for storing DB_USER information. Generally, this value is admin.
   • DB_USER is the database user.
   • DB_NAME is the name of the database from which data will be exported.
   • DB_COLLECTION is the collection of the database from which data will be exported.
   • DB_PATH is the path where the .json file is located.

   Enter the database administrator password when prompted:

   Enter password:

   The following is an example. After the command is executed, the exportfile.json file will be generated:

   ./mongoexport --host 192.168.1.21 --port 8635 --ssl --sslAllowInvalidCertificates --type json --authenticationDatabase admin -u rwuser --db test02 --collection Test --out /tmp/mongodb/export/exportfile.json

3. View the results

   If information similar to the following is displayed, the data has been successfully exported. x is the number of exported data records.

   exported x records

4. Compress the exported .json file.

   gzip exportfile.json

   Compressing the file helps reduce the time needed to transmit the data. The compressed file is exportfile.json.gz.

Importing Data

1. Log in to the ECS or whichever device you will be using to access DDS.
2. Upload the data to be imported to the ECS or the device.

   Select an uploading method based on the OS you are using.

   • In Linux, for example, you can use secure copy protocol (SCP):

     scp <IDENTITY_FILE> <REMOTE_USER>@<REMOTE_ADDRESS>:<REMOTE_DIR>

     • IDENTITY_FILE is the directory where the exportfile.json.gz file is located. The file access permission is 600.
     • REMOTE_USER is the ECS OS user.
     • REMOTE_ADDRESS is the ECS address.
     • REMOTE_DIR is the directory of the ECS to which the exportfile.json.gz file is uploaded.
   • In Windows, upload exportfile.json.gz to the ECS using file transfer tools.

3. Decompress the package.

   gzip -d exportfile.json.gz

4. Import the JSON file to the DDS database.

   The SSL connection is used as an example. If you select a common connection, delete --ssl --sslAllowInvalidCertificates from the following command.

   ./mongoimport --host <DB_ADDRESS> --port <DB_PORT> --ssl --sslAllowInvalidCertificates --type json --authenticationDatabase <AUTH_DB> -u <DB_USER> --db <DB_NAME> --collection <DB_COLLECTION> --file <DB_PATH>

   • DB_ADDRESS indicates the DB instance IP address.
   • DB_PORT indicates the database port.
   • AUTH_DB indicates the database that authenticates DB_USER. Generally, this value is admin.
   • DB_USER indicates the account name of the database administrator.
   • DB_NAME indicates the name of the database to which data will be imported.
   • DB_COLLECTION indicates the collection of the database to which data will be imported.
   • DB_PATH indicates the path where the .json file is located.

   Enter the database administrator password when prompted:

   Enter password:

   The following is an example:

   ./mongoimport --host 192.168.1.21 --port 8635 --ssl --sslAllowInvalidCertificates --type json --authenticationDatabase admin -u rwuser --db test02 --collection Test --file /tmp/mongodb/export/exportfile.json

5. View the results.

   If information similar to the following is displayed, the data has been successfully imported. x is the number of imported data records.

   imported x records