Amazon Redshift will no longer support the creation of new Python UDFs starting Patch 198. Existing Python UDFs will continue to function until June 30, 2026. For more information, see the [ blog post ](https://aws.amazon.com/blogs/big-data/amazon-redshift-python-user-defined-functions-will-reach-end-of-support-after-june-30-2026/). # History mode With history mode, you can configure your zero-ETL integrations to track every version (including updates and deletes) of your records in source tables, directly in Amazon Redshift. You can run advanced analytics on all your data, such as, run a historical analysis, build look-back reports, perform trend analysis, and send incremental updates to downstream applications built on top of Amazon Redshift. History mode is supported with multiple Amazon Redshift zero-ETL integrations, including Amazon Aurora MySQL, Amazon Aurora PostgreSQL, Amazon RDS for MySQL, and Amazon DynamoDB. History mode is also supported by several applications, such as Salesforce, SAP, ServiceNow, and Zendesk. You can turn on and off history mode for your zero-ETL integrations from the Amazon Redshift console ([https://console.aws.amazon.com/redshiftv2/](https://console.aws.amazon.com/redshiftv2/)). Use history mode to keep track of records that have been deleted or modified in the source of integration. Tracking happens in the target Amazon Redshift data warehouse. Turning on history mode does not impact the performance of regular analytic queries on these tables. After you turn on history mode, tables that you drop within the source won't be dropped in Amazon Redshift. Instead, tables will appear in a `DroppedSource` state and you can still query these tables. You can also still use the DROP and RENAME commands with regular SQL. If you want to reuse the same table name on the source, you must DROP or RENAME the corresponding `DroppedState` table before it can be replicated to Amazon Redshift. Make sure to do so before you create the table on the source. For information about what to consider when using history mode, see [Considerations when using history mode on the target](zero-etl.reqs-lims.md#zero-etl-considerations-history-mode). **To manage history mode for a zero-ETL integration** 1. Sign in to the AWS Management Console and open the Amazon Redshift console at [https://console.aws.amazon.com/redshiftv2/](https://console.aws.amazon.com/redshiftv2/). 1. From the left navigation pane, choose either the **Serverless** or **Provisioned clusters** dashboard. Then, choose **Zero-ETL integrations**. 1. Select the zero-ETL integration that you want to manage, choose **Manage history mode**. The **Manage history mode** window is displayed. 1. You can **Turn off** or **Turn on ** history mode for a target table that is replicated from a source type that has a single source table, such as, Amazon DynamoDB. When the zero-ETL integration has multiple target tables possible, you can **Turn off for all existing and future tables**, **Turn on for all existing and future tables**, or **Manage history mode for individual tables**. The default is history mode `off` when the zero-ETL integration is created. When history mode is turned `on`, the following columns are added to your target table to keep track of changes in the source. History mode `on` increases monthly usage and cost because Amazon Redshift doesn't delete any records in the target tables. Any source record that is deleted or changed creates a new record in the target, resulting in more total rows in the target with multiple record versions. Records are not deleted from the target table when deleted or modified in the source. You can manage target tables by deleting inactive records. [\[See the AWS documentation website for more details\]](http://docs.aws.amazon.com/redshift/latest/mgmt/zero-etl-history-mode.html) You can delete inactive records from a history mode table by filtering on records where the column `_record_is_active` is false. The following SQL DELETE command deletes inactive records from a table where the id column is less than or equal to 100. After you delete records, when automatic vacuum delete runs, storage for the deleted records is reclaimed. ``` DELETE FROM myschema.mytable where not _record_is_active AND id <= 100; ``` When history mode is turned `off`, Amazon Redshift makes a copy of your table in the target database with active records and without the added history columns. Amazon Redshift renames your table to `table-name_historical_timestamp` for your use. You can drop this copy of your table if you no longer need it. You can rename these tables using the ALTER TABLE command. For example: ``` ALTER TABLE [schema-name.]table-name_historical_timestamp RENAME TO new_table_name; ``` For more information, see [ALTER TABLE](https://docs.aws.amazon.com/redshift/latest/dg/r_ALTER_TABLE.html) in the *Amazon Redshift Database Developer Guide*. You can also manage history mode using SQL commands CREATE DATABASE and ALTER DATABASE. For more information about how to set HISTORY\$1MODE, see [CREATE DATABASE](https://docs.aws.amazon.com/redshift/latest/dg/r_CREATE_DATABASE.html) and [ALTER DATABASE](https://docs.aws.amazon.com/redshift/latest/dg/r_ALTER_DATABASE.html) in the *Amazon Redshift Database Developer Guide*.