Ops

VACUUM

This command works differently depending on working environment: Delta, Apache Spark, or Apache Iceberg table.

VACUUM removes all files from the table directory that are

• not managed by Delta
• outdated: data files that are no longer in the latest state of the transaction log for the table and are older than a retention threshold.
  • default retention threshold: 7 days
  • not based on modification timestamps on the storage system

  • you lose the ability to time travel back to a version older than the specified data retention period.

VACUUM skip all directories that

• start with _, including _delta_log

Time travel

Docs: Azure Databricks

• Similar to Query an older snapshot of a table

DROP FEATURE

ALTER TABLE <table-name> DROP FEATURE <feature-name> [TRUNCATE HISTORY]

is one of

• typeWidening
• columnMapping
• deletionVectors
• v2Checkpoint
• checkConstraints
• vacuumProtocolCheck