create sets up and creates a new workflow. The workflow name should not conflict with that of an existing workflow.

show displays useful information about a workflow – including recent logs.

status (or progress) reports the progress of a workflow by showing the percentage of data copied across targets, if workflow is in copy state, and the replication lag between the target and the source once the copy phase is completed. It also shows the current state of traffic for the tables involved in the workflow.

It is too expensive to get real-time row counts of tables, using count(*), say. So we use the statistics available in the information_schema to approximate copy progress. This data can be significantly off (up to 50-60%) depending on the utilization of the underlying mysql server resources. You can manually run ANALYZE TABLE to update the statistics if so desired.

mirrortraffic mirrors a percentage of traffic forward for the tablet-types specified.

mirrortraffic must be run before switchtraffic. switchtraffic will automatically remove any mirror rules that were created by mirrortraffic.

switchtraffic switches traffic forward for the tablet-types specified. You can switch all traffic with just one command, and this is the default behavior. Note that you can now switch replica, rdonly, and primary traffic in any order.

reversetraffic switches traffic in the reverse direction for the tablet-types specified. The traffic should have been previously switched forward using SwitchTraffic for the cells and tablet-types specified.

cancel can be used if a workflow was created in error or was misconfigured and you prefer to create a new workflow instead of fixing this one. cancel can only be called if no traffic has been switched. It removes vreplication-related artifacts like rows from the vreplication and copy_state tables in the sidecar _vt database along with routing rules and blacklisted tables from the topo and, by default, the target tables on the target keyspace (see --keep-data and --rename-tables).

complete is used after all traffic has been switched. It removes vreplication-related artifacts like rows from vreplication and copy_state tables in the sidecar _vt database along with routing rules and and blocklisted tables from the topo. By default, the source tables are also dropped on the target keyspace (see --keep-data and --rename-tables).

This is a flag for the Create sub-command and it takes a string where the valid values are LEAVE (leave the MySQL auto_increment clauses in place), REMOVE (remove the clauses), and REPLACE (replace them with Vitess sequences). When REPLACE is specifed then not only are the MySQL auto_increment clauses removed when copying the table schemas from the source keyspace to the target, but the target keyspace's VSchema is also updated so that auto increment values will be retrieved from the sequence table (which can automatically be created using the two flags covered below).

This is also a flag for the Create sub-command and it takes a string where the value must be an existing unsharded keyspace. This keyspace will then be used to create the backing sequence tables if they do not already exist, provided you also request that the target sequences be setup and initialized using the next flag below.

If specified for the SwitchTraffic sub-command, then when switching write (primary tablet) traffic for tables that are being moved from an unsharded keyspace to a sharded one, initialize any sequences being used by those tables on the target. They are initialized using the current maximum value for the column across all shards on the target.

Normally the workflow starts immediately after it is created. If this flag is set to false then the workflow is in a Stopped state until you explicitly start it.

Comma seperated list of Cell(s) and/or CellAlias(es) to replicate from.

If true, any secondary keys are dropped from the table definitions on the target shard(s) as we first initialize the tables for the copy phase. The exact same key definitions are then re-added when the copy phase completes for each table.

With this method all secondary index records for the table are generated in one bulk operation. This should significantly improve the overall copy phase execution time on large tables with many secondary keys — especially with MySQL 8.0.31 and later due to InnoDB's support for parallel index builds. This is logically similar to the mysqldump --disable-keys option.

While executing SwitchTraffic we ensure that the VReplication lag for the workflow is less than this duration, otherwise report an error and don't attempt the switch. The calculated VReplication lag is the estimated maximum lag across workflow streams between the last event seen at the source and the last event processed by the target (which would be a heartbeat event if we're fully caught up). Usually, when VReplication has caught up, this lag should be very small (under a second).

While switching write traffic, we temporarily make the source databases read-only, and wait for the targets to catchup. This means that the application can effectively be partially down for this cutover period as writes will pause or error out. While switching write traffic this flag can ensure that you only switch traffic if the current lag is low, thus limiting this period of write-unavailability and avoiding it entirely if we're not likely to catch up within the --timeout) window.

While switching read traffic this can also be used to set an approximate upper bound on how stale reads will be against the replica tablets when using @replica shard targeting.

This flag allows you to specify what to do with DDL SQL statements when they are encountered in the replication stream from the source. The values can be as follows:

• IGNORE: Ignore all DDLs (this is also the default, if a value for on-ddl is not provided).
• STOP: Stop when DDL is encountered. This allows you to make any necessary changes to the target. Once changes are made, updating the workflow state to Running will cause VReplication to continue from just after the point where it encountered the DDL. Alternatively you may want to Cancel the workflow and create a new one to fully resync with the source.
• EXEC: Apply the DDL, but stop if an error is encountered while applying it.
• EXEC_IGNORE: Apply the DDL, but ignore any errors and continue replicating.

During Complete or Cancel operations, the tables are renamed instead of being deleted. Currently the new name is _<table_name>_old.

We use the same renaming logic used by pt-online-schema-change. Such tables are automatically skipped by VReplication if they exist on the source.

SwitchTraffic for primary tablet types, 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 mechanism using ReverseTraffic. This reverse workflow name is that of the original workflow concatenated with _reverse.

If set to false these reverse replication streams will not be created and you will not be able to rollback once you have switched write traffic over to the target.

Specifying this flag causes all DATETIME fields to be converted from the given time zone into UTC. It is expected that the application has stored all DATETIME fields, in all tables being moved, in the specified time zone. On the target these DATETIME values will be stored in UTC.

As a best practice, Vitess expects users to run their MySQL servers in UTC. So we do not specify a target time zone for the conversion. It is expected that the time zone tables have been pre-populated on the target mysql servers.

Any reverse replication streams running after a SwitchWrites will do the reverse date conversion on the source.

Note that selecting the DATETIME columns from the target will now give the times in UTC. It is expected that the application will perform any conversions using, for example, SET GLOBAL time_zone = 'US/Pacific'or convert_tz().

Also note that only columns of DATETIME data types are converted. If you store DATETIME values as VARCHAR or VARBINARY strings, setting this flag will not convert them.

If set, the workflow will stop once the Copy phase has been completed i.e. once all tables have been copied and VReplication decides that the lag is small enough to start replicating, the workflow state will be set to Stopped.

Source tablet types to replicate from (e.g. PRIMARY, REPLICA, RDONLY). The value specified impacts tablet selection for the workflow.

For primary tablets, SwitchTraffic first stops writes on the source primary 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 timeout the command will error out. For setups with high write qps you may need to increase this value.