> For the complete documentation index, see [llms.txt](https://mariadb.com/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mariadb.com/docs/server/server-usage/storage-engines/innodb/innodb-data-scrubbing.md).

# InnoDB Data Scrubbing

{% hint style="warning" %}
Most of the background and redo log scrubbing code has been removed in [MariaDB 10.5.2](/docs/release-notes/community-server/old-releases/10.5/10.5.2.md). See [MDEV-15528](https://jira.mariadb.org/browse/MDEV-15528) and [MDEV-21870](https://jira.mariadb.org/browse/MDEV-21870).
{% endhint %}

Sometimes there is a requirement that when some data is deleted, it is really gone. This might be the case when one stores user's personal information or some other sensitive data. Normally though, when a row is deleted, the space is only marked as free on the page. It may eventually be overwritten, but there is no guarantee when that will happen. A copy of the deleted rows may also be present in the log files.

Support for [InnoDB](/docs/server/server-usage/storage-engines/innodb.md) data scrubbing: Background threads periodically scan tablespaces and logs and remove all data that should be deleted. The number of background threads for tablespace scans is set by [innodb-encryption-threads](/docs/server/server-usage/storage-engines/innodb/innodb-system-variables.md). Log scrubbing happens in a separate thread.

To configure scrubbing one can use the following variables:

|                                                                                                                                                                        |           |                                                                                                 |
| ---------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------- | ----------------------------------------------------------------------------------------------- |
| [innodb-background-scrub-data-check-interval](/docs/server/server-usage/storage-engines/innodb/innodb-system-variables.md#innodb_background_scrub_data_check_interval) | Seconds   | Check at this interval if tablespaces needs scrubbing. Deprecated and ignored.                  |
| [innodb-background-scrub-data-compressed](/docs/server/server-usage/storage-engines/innodb/innodb-system-variables.md#innodb_background_scrub_data_compressed)         | Boolean   | Enable scrubbing of compressed data by background threads. Deprecated and ignored.              |
| [innodb-background-scrub-data-interval](/docs/server/server-usage/storage-engines/innodb/innodb-system-variables.md#innodb_background_scrub_data_interval)             | Seconds   | Scrub spaces that were last scrubbed longer than this many seconds ago. Deprecated and ignored. |
| [innodb-background-scrub-data-uncompressed](/docs/server/server-usage/storage-engines/innodb/innodb-system-variables.md#innodb_background_scrub_data_uncompressed)     | Boolean   | Enable scrubbing of uncompressed data by background threads. Deprecated and ignored.            |
| [innodb-immediate-scrub-data-uncompressed](/docs/server/server-usage/storage-engines/innodb/innodb-system-variables.md#innodb_immediate_scrub_data_uncompressed)       | Boolean   | Enable scrubbing of uncompressed data.                                                          |
| [innodb-scrub-log](/docs/server/server-usage/storage-engines/innodb/innodb-system-variables.md#innodb_scrub_log)                                                       | Boolean   | Enable redo log scrubbing. Deprecated and ignored.                                              |
| [innodb-scrub-log-speed](/docs/server/server-usage/storage-engines/innodb/innodb-system-variables.md#innodb_scrub_log_speed)                                           | Bytes/sec | Redo log scrubbing speed in bytes/sec. Deprecated and ignored.                                  |

Redo log scrubbing did not fully work as intended, and was deprecated and ignored in [MariaDB 10.5.2](/docs/release-notes/community-server/old-releases/10.5/10.5.2.md) ([MDEV-21870](https://jira.mariadb.org/browse/MDEV-21870)). If old log contents should be kept secret, enabling [innodb\_encrypt\_log](/docs/server/server-usage/storage-engines/innodb/innodb-system-variables.md#innodb_encrypt_log) or setting a smaller [innodb\_log\_file\_size](/docs/server/server-usage/storage-engines/innodb/innodb-system-variables.md#innodb_log_file_size) could help.

The [Information Schema INNODB\_TABLESPACES\_SCRUBBING table](/docs/server/reference/system-tables/information-schema/information-schema-tables/information-schema-innodb-tables/information-schema-innodb_tablespaces_scrubbing-table.md) contains scrubbing information.

## Thanks

* Scrubbing was donated to the MariaDB project by Google.

<sub>*This page is licensed: CC BY-SA / Gnu FDL*</sub>

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