Snowflake Time Travel

Here is a detailed guide on how to use Snowflake Time Travel:

1. Enable Time Travel on your Snowflake account:

To use Time Travel, your account must have Time Travel enabled. This can be done by contacting your Snowflake account representative or submitting a support ticket.

2. Enable Time Travel on a specific table:

Once Time Travel is enabled for your account, you can help it on a specific table by setting the “TIME_TRAVEL” attribute to several days. For example, to allow Time Travel for seven days on a table named “my_table”, you can run the following SQL command:

This means you can query the data in “my_table” as it existed up to 7 days ago.

3. Querying data with Time Travel:

To query data in a table as it existed at a specific time, you can use the special syntax “AS OF” followed by a timestamp or a number of days in the past. For example, to query the data in “my_table” as it existed three days ago, you can run the following SQL command:

Or, if you prefer to specify the number of days directly, you can use the following command:

Note that Time Travel queries are read-only, so you cannot modify or delete data using Time Travel.

4. Time Travel retention:

By default, Snowflake retains Time Travel data for one day. However, this can be configured per table by setting the “TIME_TRAVEL_CLONE_RETENTION_TIME” attribute on the table. For example, to retain Time Travel data for 30 days on a table named “my_table”, you can run the following SQL command:

This means you can query the data in “my_table” as it existed up to 30 days ago.

5. Time Travel costs:

Using Time Travel incurs additional storage costs in Snowflake. The price is based on the amount of data stored in the Time Travel history for each table. To estimate the cost of Time Travel for a table, you can use the Snowflake pricing calculator.

6. Time Travel for schema and database objects:

In addition to tables, you can enable Time Travel on schema and database objects, such as views, stages, and user-defined functions. To allow Time to Travel for a schema, you can set the “TIME_TRAVEL” attribute on the schema to several days. For example:

This means you can query the schema objects as they existed up to 7 days ago. To query a view as it existed at a specific time, you can use the “AS OF” syntax in the SELECT statement, similar to querying a table.

7. Time Travel for data changes:

In addition to querying data as it existed at a specific time, you can also track changes to data over time using Snowflake’s “CHANGE_TRACKING” feature. When you enable change tracking on a table, Snowflake captures all changes, including inserts, updates, and deletes. You can then query the changes to the data using the “FOR SYSTEM_TIME AS OF” syntax. For example:

This query returns the row with ID 1234 as it existed at the specified timestamp and any changes made to that row before or after it.

8. Time Travel for compliance:

Snowflake Time Travel can be helpful for compliance purposes, as it allows you to track and audit changes to data over time. You can use Time Travel to provide evidence of compliance with data retention, privacy, and security regulations. For example, you can use Time Travel to demonstrate that you retained data for the required time or to show that you protected sensitive data by restricting access to it.

9. Time Travel for disaster recovery:

In addition to compliance, Snowflake Time Travel can also be helpful for disaster recovery. If you accidentally delete or modify data, you can use Time Travel to recover it as it existed before the deletion or modification. You can also use Time Travel to recover from other disasters, such as system failures or data corruption.

10. Time Travel and storage costs:

It’s important to note that enabling Time Travel can increase the storage cost of your Snowflake account. Each additional day of Time Travel enabled on a table, schema, or database object increases the storage required to store the data. However, Snowflake provides several options to help you manage your storage costs, including automatic data retention policies and the ability to clone tables and objects at specific points in time.

11. Time Travel and Performance:

Enabling Time Travel can also impact query performance, especially if you need to query data over a long period or if you have many changes to your data. Snowflake provides several features to help you optimize query performance with Time Travel, including automatic data pruning and partitioning.

12. Time Travel and security:

Snowflake Time Travel is designed with security in mind. When you enable Time Travel on a table or object, Snowflake creates a read-only snapshot of the data at the specified point in time. This snapshot is stored separately from the live data; only authorized users can access it. Snowflake also provides several security features to help you control access to Time Travel data, including role-based access control and multi-factor authentication.

13. Time Travel and data governance:

Finally, Snowflake Time Travel can be a valuable tool for data governance. By enabling Time Travel on your tables and objects, you can track changes to your data over time and maintain a complete record of all data modifications. This can help you ensure data accuracy, compliance, and accountability and provide a full audit trail for your data.

Snowflake Time Travel is a powerful feature that can benefit data management, compliance, and disaster recovery. By enabling Time Travel on your tables, schema objects, and databases, you can track changes to data over time, audit data usage and compliance, and recover from disasters.