The Databricks DBIO package provides transactional writes to cloud storage for Apache Spark jobs. This solves a number of performance and correctness issues that come when Spark is used in a cloud-native setting (for example, writing directly to storage services like Azure Blob storage).
When DBIO transactional commit is enabled, metadata files starting with
_committed_<id> will accompany data files created by Spark jobs. Generally you shouldn’t alter these files directly. Rather, use the
To clean up uncommitted files left over from Spark jobs, use the
VACUUM command to remove them. Normally
VACUUM happens automatically after Spark jobs complete, but you can also run it manually if a job is aborted.
VACUUM ... RETAIN 1 HOUR removes uncommitted files older than one hour.
- Avoid vacuuming with a horizon of less than one hour. It can cause data inconsistency.
- You cannot use
VACUUMdirectly on cloud storage. To vacuum storage, you must mount it to DBFS and run
VACUUMon the mounted directory.
Also see Vacuum.
-- recursively vacuum an output path VACUUM '/path/to/output/directory' [RETAIN <N> HOURS] -- vacuum all partitions of a catalog table VACUUM tableName [RETAIN <N> HOURS]
// recursively vacuum an output path spark.sql("VACUUM '/path/to/output/directory' [RETAIN <N> HOURS]") // vacuum all partitions of a catalog table spark.sql("VACUUM tableName [RETAIN <N> HOURS]")