Destination Cockroach #

The extracted replicant-cli will be referred to as the $REPLICANT_HOME directory in the proceeding steps.

I. Set up Connection Configuration #

  1. From $REPLICANT_HOME, navigate to the sample Cockroach connection configuration file:

    vi conf/conn/cockroach.yaml
  2. The configuration file has two parts:

    • Parameters related to target Cockroach server connection.
    • Parameters related to stage configuration.

    You can store your connection credentials in a secrets management service and tell Replicant to retrieve the credentials. For more information, see Secrets management.

    Otherwise, you can put your credentials like usernames and passwords in plain form like the sample below:

    type: COCKROACH
    host: localhost #Replace localhost with your Cockroach host
    port: 26257 #Replace the 26257 with the port of your host
    username: 'replicant' #Replace replicant with the username of your user that connects to your Cockroach server
    password: 'Replicant#123' #Replace Replicant#123 with your user's password
    max-connections: 30 #Specify the maximum number of connections Replicant can open in Cockroach
    max-retries: #Number of times any operation on the system will be re-attempted on failures.
    retry-wait-duration-ms : #Duration in milliseconds replicant should wait before performing then next retry of a failed operation
    • Make sure the specified user has CREATE TABLE privilege on the catalogs/schemas into which replicated tables should be created.

    • If you want Replicant to create catalogs/schemas for you on the target CockroachDB system, then you also need to grant CREATE DATABASE/CREATE SCHEMA privileges to the user.

    • If this user does not have CREATE DATABASE privilege, then create a database manually with name io and grant all privileges for it to the user specified here. Replicant uses this database for internal checkpointing and metadata management.

      The database/schema of your choice on a different instance of your choice name can be configured using the metadata config feature. For more information, see Metadata Configuration.

    It is possible to use a local, native, or an external stage like S3 to hold the data files and then load them on the target Cockroach database from there. This section allows you to specify the details Replicant needs to connect to and use a specific stage.

    • type: The stage type. Allowed stages are LOCAL_FS, NATIVE, and S3.
      • LOCAL_FS: Stage type where users can specify the external-io-dir of the Cockroach system.
      • NATIVE: stage type where replicant uses cockroach nodelocal upload utility to upload the data files for IMPORT to load into Cockroach. Users need to specify other details:
        • conn-url: URL of the CockroachDB server as required for the cockroach nodelocal upload command.
        • user: User with appropriate privilege to be able to run this command.
      • S3 : Stage type where Replicant uses the specified S3 account to hold the data files for IMPORT to load into Cockroach.

    For a NATIVE stage, you must install Cockroach on the host running Replicant with the following four steps:

    1. Get the latest binary:

      wget -qO- | tar xvz
    2. Copy the binary into your PATH so it’s easy to execute cockroach commands from any shell:

      cp -i cockroach-v20.1.0-beta.1.linux-amd64/cockroach /usr/local/bin/
    3. If you get a permissions error, prefix the command with sudo.

    4. Verify that cockroach nodelocal upload is a valid command.

    The target CockroachDB version must support the cockroach nodelocal upload command for this stage type to work.

II. Set up Applier Configuration #

  1. From $REPLICANT_HOME, naviagte to the sample Cockroach applier configuration file:
    vi conf/dst/cockroach.yaml
  2. Make the necessary changes as follows:
     threads: 16 #Specify the maximum number of threads Replicant should use for writing to the target
     #If bulk-load is used, Replicant will use the native bulk-loading capabilities of the target database
       enable: true|false #Set to true if you want to enable bulk loading
       type: FILE|PIPE #Specify the type of bulk loading between FILE and PIPE
       method: IMPORT # COPY, IMPORT
       max-files-per-bulk-load: 10 #Specify the maximum number of files that can be replicated per bulk-load
       node-id: 1
       serialize: false|true #Serialize must be true for method IMPORT
       serialize-stage-upload: false
    # bulk-load:
    #   enable: true
    #   type: FILE   # PIPE, FILE
    #   method: COPY # COPY, IMPORT
    #   max-files-per-bulk-load: 1
    #   serialize: false

For a detailed explanation of configuration parameters in the applier file, read Applier Reference.