SwitchWrites

Route writes to target keyspace in a vreplication workflow

Command

SwitchWrites  [-filtered_replication_wait_time=30s] [-cancel] [-reverse_replication=true] 
              [-dry-run] <keyspace.workflow>

Description

SwitchWrites is used to switch writes for tables in a MoveTables workflow or for entire keyspace in the Reshard workflow away from the master in the source keyspace to the master in the target keyspace

Parameters

-filtered_replication_wait_time

optional
default 30s

SwitchWrites first stops writes on the source master and waits for the replication to the target to catchup with the point where the writes were stopped. If the wait time is longer than filtered_replication_wait_time the command will error out. For setups with high write qps you may need to increase this value.

-cancel

optional
default false

If a previous SwitchWrites returned with an error you can restart it by running the command again (after fixing the issue that caused the failure) or the SwitchWrites can be canceled using this parameter. Only the SwitchWrites is cancelled: the workflow is set to Running so that replication continues.

-reverse_replication

optional
default true

SwitchWrites, by default, starts a reverse replication stream with the current target as the source, replicating back to the original source. This enables a quick and simple rollback. This reverse workflow name is that of the original workflow concatenated with \_reverse.

-dry-run

optional
default false

You can do a dry run where no actual action is taken but the command logs all the actions that would be taken by SwitchReads.

keyspace.workflow

mandatory

Name of target keyspace and the associated workflow to SwitchWrites for.