Data Scrubbing¶
Availability: | This feature is tech preview quality |
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The DELETE
statement does the following:
- Marks the rows as deleted
- Added to
unused
- Records the deleted row position
- Records the time when delete was committed
The data is not immediately removed from disk storage. When a new row is inserted, the row is stored without fragmentation in a page with free space. The deleted data remains on the disk until new data overwrites it.
Using Data Scrubbing, you have two options to remove the data and reclaim the space:
Once enabled, data scrubbing works automatically on each tablespace.
To enable data scrubbing, you must enable either one or both of the following variables:
innodb-background-scrub-data-uncompressed
innodb-background-scrub-data-compressed
Uncompressed tables can also be scrubbed immediately, independent of key
rotation or background threads. Setting the variable
innodb-immediate-scrub-data-uncompressed
enables this operation. This variable does not support operations on compressed tables.
For background scrubbing, you must set the innodb_encryption_threads
variable to a value greater than zero when you enable data scrubbing. Intermediate scrubbing does not use encryption threads. A separate thread performs log scrubbing.
System Variables¶
-
variable
innodb_background_scrub_data_compressed
¶ Command Line: --innodb-background-scrub-data-compressed
Dynamic: Yes Scope: Global Variable Type: Boolean Default Value: OFF
Enables compressed data scrubbing.
-
variable
innodb_background_scrub_data_uncompressed
¶ Command Line: --innodb-background-scrub-data-uncompressed
Dynamic: Yes Scope: Global Variable Type: Boolean Default Value: OFF
Enables uncompressed data scrubbing.
-
variable
innodb_scrub_log
¶ Command Line: --innodb-scrub-log
Dynamic: No Scope: Global Variable Type: Boolean Default Value: OFF
Enables redo log scrubbing.
-
variable
innodb_scrub_log_speed
¶ Command Line: --innodb-scrub-log-speed
Dynamic: Yes Scope: Global Variable Type: Numeric Default Value: 256
Defines the scrubbing speed in bytes/sec of the redo log.
-
variable
innodb_immediate_scrub_data_uncompressed
¶ Command Line: --innodb-immediate-scrub-data-uncompressed
Dynamic: Yes Scope: Global Variable Type: Boolean Default Value: OFF
Enables data scrubbing of uncompressed data.
See also
- Vault Documentation
- https://www.vaultproject.io/docs/index.html
- General-Purpose Keyring Key-Management Functions
- https://dev.mysql.com/doc/refman/8.0/en/keyring-udfs-general-purpose.html
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