Modifying Table Replica

Explains how to edit the properties of a replica using the Control System and the CLI.

Modifying a Table Replica Using the Control System

About this task

To modify the properties of a table replica:

Procedure

Go to the table information page.
See Viewing Table Information.
Click Replicas to go to that tab.
Click associated with the replica to modify.
The Edit Replica page displays.

Make changes to the following as desired:

Path to Replica

The path to the replica.

For a table on the local cluster, start the path at the volume mount point. For example, for a table named testdst under a volume with a mount point at /volume1, specify the following path: /volume1/testdst
For a table on another cluster, you must also specify the cluster name in the path. For example, for a table named customerdst under volume1 in the sanfrancisco cluster, specify the following path: /mapr/sanfrancisco/volume1/customerdst

NOTE For replication to a table, the command will fail if the replica path you specify points to a table that already exists.

Replication State

Specify whether or not to start replication by choosing one of the following:

Automatic Setup — Creates the table on the destination cluster, registers the table on the destination cluster as a replica, adds the current table as an upstream source, copies the content of the current table into the replica, and start replication.
Pause Replication — Creates the table on the destination cluster, registers the table on the destination cluster as a replica, adds the current table as an upstream source, but prevents replication from immediately starting after. Pausing replica like this allows you to load the data into the replica from the current table, after which you can restart replication.

Multi-Master Setup

(Available only with Automatic Setup) Multi-master topology, in which there are two primary-secondary relationships, with each table playing both primary and secondary roles. Client applications update both tables and each table replicates updates to the other.

See Primary-Secondary Replication.

If this is not selected, table replication will be basic primary-secondary topology, which is the default. In this topology, you replicate one way from source tables to replicas. The replicas can be in a remote cluster or in the cluster where the source tables are located.

See Primary-Secondary Replication.

NOTE Access control expressions on the replica that control permissions for updates to column families and columns are irrelevant because all updates from a source table arrive at a replica after having been authenticated at a gateway, which has the implicit authority to update replicas.

Set the following optional properties:

Throttle	Specify whether (Yes) or not (No) to throttle replication operations. Throttle the replication stream to minimize the impact of the replication process on incoming operations during periods of heavy load.
Replicate Synchronously	Specify whether replication is synchronous (Yes) or asynchronous (No).
Encrypt On Wire	Specify whether (Yes) or not (No) to enable on-wire encryption. If you enable this, the local cluster and any other cluster that is part of the replication process must be enabled for security.
Compress On Wire	The type of on-wire compression. Choose one of the following: Inherited OFF LZF LZ4 ZLib

Choose whether to:
- For JSON table replica:
  - Replicate Entire Document
  - Replicate Selected Field Paths — Specify the full path to the field in dotted notation. For example, suppose the table contained JSON documents that were of this general structure:
```
{
     "_id" : "ID",
     "a" :
          {
               "b" : 
                    {
                         "c" : "value",
                    },
               "e" : "value"
          }
}
```
    To replicate field c, you must specify a.b.c as the field path. Do not use quotation marks and do not include spaces after each dot. Click:
    - Add Field to add another field to replicate.
    - to remove a field.
- For Binary table replica:
  - Replicate All Column Families
  - Replicate Selected Column Families — Specify the column family name and select:
    - Include All Columns — to replicate all columns associated with the column family.
    - Assign Columns — to specify specific columns associated with the column family. To add more columns, click +.
Click Edit Replica for the changes to take effect.

Modifying a Table Replica Using the CLI or REST API

About this task

The basic command to modify a table replica is:

maprcli table replica edit -path <table path> -replica <replica table path>

To run this command, your user ID must have the following permissions:

readAce and writeAce on both the source volume and the target volume
lookupdir on directories in the paths of both tables
readperm and replperm permissions on the source table

For complete reference, see table replica edit.