CREATE SCHEDULE FOR CHANGEFEED

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CREATE SCHEDULE FOR CHANGEFEED allows you to create a scheduled changefeed to export data out of CockroachDB. Scheduled changefeeds have the scale, observability, and endpoint sink options that changefeed jobs include, with the convenience of setting a regular schedule. A changefeed job created with CREATE SCHEDULE FOR CHANGEFEED performs a one-time table scan using the initial scan functionality to create an export of your table data.

For more detail on using changefeeds to create an export of your table data, see Export Data with Changefeeds.

Required privileges

Note:

Starting in v22.2, CockroachDB introduces a new system-level privilege model that provides finer control over a user's privilege to work with the database, including creating and managing changefeeds.

There is continued support for the legacy privilege model for changefeeds in v23.1, however it will be removed in a future release of CockroachDB. We recommend implementing the new privilege model that follows in this section for all changefeeds.

You can grant a user the CHANGEFEED privilege to allow them to create changefeeds on a specific table:

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GRANT CHANGEFEED ON TABLE example_table TO user;

When you grant a user the CHANGEFEED privilege on a set of tables, they can:

These users will be able to create changefeeds, but they will not be able to run a SELECT query on that data directly. However, they could still read this data indirectly if they have read access to the sink.

To restrict a user's access to changefeed data and sink credentials, enable the changefeed.permissions.require_external_connection_sink.enabled cluster setting. When you enable this setting, users with the CHANGEFEED privilege on a set of tables can only create changefeeds into external connections.

Privilege model

The following summarizes the operations users can run when they have changefeed privileges on a table:

Granted privileges Usage
CHANGEFEED Create changefeeds on tables.
Manage changefeed jobs on tables.
CHANGEFEED + USAGE on external connection Create changefeeds on tables to an external connection URI.
Manage changefeed jobs on tables.
Note: If you need to manage access to changefeed sink URIs, set the changefeed.permissions.require_external_connection_sink.enabled=true cluster setting. This will mean that users with these privileges can only create changefeeds on external connections.
SELECT Create a sinkless changefeed that emits messages to a SQL client.
Deprecated CONTROLCHANGEFEED role option + SELECT Create changefeeds on tables.

You can add CHANGEFEED to the user or role's default privileges with ALTER DEFAULT PRIVILEGES:

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ALTER DEFAULT PRIVILEGES GRANT CHANGEFEED ON TABLES TO user;
Note:

Users with the CONTROLCHANGEFEED role option must have SELECT on each table, even if they are also granted the CHANGEFEED privilege. The CONTROLCHANGEFEED role option will be deprecated in a future release.

Legacy privilege model

To create a changefeed, the user must be a member of the admin role or have the CREATECHANGEFEED parameter set.

Synopsis

CREATE SCHEDULE IF NOT EXISTS schedule_label FOR CHANGEFEED changefeed_target , INTO changefeed_sink WITH changefeed_option , INTO changefeed_sink WITH changefeed_option , AS SELECT target_list FROM insert_target where_clause RECURRING crontab WITH SCHEDULE OPTIONS schedule_option ( schedule_option )

Parameters

Parameter Description
IF NOT EXISTS A scheduled changefeed should not be created if the schedule_label already exists. You will receive an error if the schedule label already exists, or if schedule_label is not defined when using IF NOT EXISTS.
schedule_label The name for the scheduled changefeed. This is optional and does not need to be unique. If you do not define a name, the label will default to CHANGEFEED with the timestamp of when you created the schedule.
changefeed_targets The tables to target with the changefeed. For example, movr.users, movr.rides.
changefeed_sink The changefeed sink URI.
changefeed_option The options to control the behavior of your changefeed. For example, WITH format = csv, full_table_name. See Changefeed options for a list of available options.
target_list The columns to emit data from if you're using a CDC query expression.
insert_target The target tables for the changefeed if you're using a CDC query expression.
where_clause An optional WHERE clause to apply filters to the table if you're using a CDC query expression.
crontab The frequency of the changefeed. The schedule is specified as a STRING in crontab format. All times in UTC. For example, '@daily', '@hourly', '1 0 * * *'.
schedule_option The schedule options to control the schedule's behavior. For example, first_run = now. See Schedule options.

Changefeed options

You can include the changefeed options listed on the CREATE CHANGEFEED page to modify the behavior of your changefeed. The following options are not compatible with scheduled changefeeds:

  • diff
  • end_time
  • mvcc_timestamp
  • resolved
  • updated

Scheduled changefeeds have the initial_scan = 'only' option included implicitly. You cannot specify initial_scan as 'yes' or 'no'.

Schedule options

Option Value Description
first_run TIMESTAMP / now Execute the first run of the schedule at this time. If you do not specify first_run, the schedule will execute based on the next RECURRING time set by the crontab.
on_execution_failure retry / reschedule / pause Determine how the schedule handles an error.

retry: Retry the changefeed immediately.

reschedule: Reschedule the changefeed based on the RECURRING expression.

pause: Pause the schedule. This requires that you resume the schedule manually.

Default: reschedule
on_previous_running start / skip / wait Control whether the changefeed schedule should start a changefeed if the previous scheduled changefeed is still running.

start: Start the new changefeed anyway, even if the previous one is running.

skip: Skip the new changefeed and run the next changefeed based on the RECURRING expression.

wait: Wait for the previous changefeed to complete.

Default: wait

Examples

Before running any of the examples in this section, it is necessary to enable the kv.rangefeed.enabled cluster setting. If you are working on a CockroachDB Serverless cluster, this cluster setting is enabled by default.

The Changefeed Sinks page provides detail on the available sinks for your change data messages and connection URIs. We recommend using external connections to interact with external sinks. The examples in this section use an external connection URI for the changefeed sink.

Create a scheduled changefeed

The following statement sets up a scheduled changefeed named users_rides_nightly that will send changefeed messages in CSV format 1 minute past midnight every night. As soon as the statement is run, the first changefeed run will execute immediately:

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CREATE SCHEDULE users_rides_nightly FOR CHANGEFEED INTO 'external://kafka-sink' WITH format=csv RECURRING '1 0 * * *' WITH SCHEDULE OPTIONS first_run=now, on_execution_failure=retry, on_previous_running=skip;

The schedule options control the schedule's behavior:

  • If it runs into an error, on_execution_failure=retry will ensure that the schedule retries the changefeed immediately.
  • If the previous scheduled changefeed is still running, on_previous_running=skip will skip a new changefeed at the next scheduled time.

Create a scheduled changefeed with CDC queries

You can use CDC queries with scheduled changefeeds to define expression syntax that selects columns and applies filters to further restrict or transform the data in your changefeed messages. When you add this expression syntax to your changefeed statement, you can only target one table.

For guidance on syntax and more example use cases, see Change Data Capture Queries.

This scheduled changefeed filters for the usage of promotion codes in the movr database and sends the changefeed messages on a daily basis:

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CREATE SCHEDULE FOR CHANGEFEED INTO 'external://kafka-sink' AS SELECT user_id, usage_count FROM movr.user_promo_codes WHERE usage_count > 1 RECURRING '@daily' WITH SCHEDULE OPTIONS first_run=now, on_execution_failure=reschedule, on_previous_running=skip;

View scheduled changefeed details

To show all scheduled changefeeds:

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SHOW SCHEDULES FOR CHANGEFEED;

To view the details of only running scheduled changefeeds:

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SHOW RUNNING SCHEDULES FOR CHANGEFEED;

To view the details of only paused scheduled changefeeds:

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SHOW PAUSED SCHEDULES FOR CHANGEFEED;

To view the details of a specific scheduled changefeed:

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SHOW SCHEDULE {schedule ID};

To pause a scheduled changefeed:

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PAUSE SCHEDULE {schedule ID};

To resume a scheduled changefeed:

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RESUME SCHEDULE {schedule ID};

To delete a scheduled changefeed:

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DROP SCHEDULE {schedule ID};

To see the full CREATE SCHEDULE statement for the scheduled changefeed:

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SHOW CREATE SCHEDULE {schedule ID};

See also


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