This command updates Delta table metadata to the Unity Catalog service. For non-Delta tables, it repairs the table’s partitions and updates the Hive metastore.
Delta tables: When executed with Delta tables using the
SYNC METADATAargument, this command reads the delta log of the target table and updates the metadata info to the Unity Catalog service.
Non-Delta tables: When executed with non-Delta tables, this command recovers all the partitions in the directory of a non-Delta table and updates the Hive metastore.
The name of the table.
Since: Databricks Runtime 10.0
When creating a non-Delta table using the
PARTITIONED BYclause, partitions are generated and registered in the Hive metastore. However, if the partitioned table is created from existing data, partitions are not registered automatically in the Hive metastore; you must run
MSCK REPAIR TABLEto register the partitions.
Another way to recover partitions is to use ALTER TABLE RECOVER PARTITIONS.
If the table is cached, the command clears the table’s cached data and all dependents that refer to it. The cache will be lazily filled the next time the table or dependents are accessed.
ADD command adds new partitions to the session catalog for all sub-folders in the base table folder that don’t belong to any table partitions. ADD is the default argument if no other option is specified.
DROP command drops all partitions from the session catalog that have non-existing locations in the file system.
SYNC is the combination of DROP and ADD.
Reads the delta log of the target table and updates the metadata info in the Unity Catalog service. To run this command, you must have MODIFY and SELECT privileges on the target table and USAGE of the parent schema and catalog. This command with this argument will fail if the target table is not stored in Unity Catalog.
-- create a partitioned table from existing data /tmp/namesAndAges.parquet > CREATE TABLE t1 (name STRING, age INT) USING parquet PARTITIONED BY (age) LOCATION "/tmp/namesAndAges.parquet"; -- SELECT * FROM t1 does not return results > SELECT * FROM t1; -- run MSCK REPAIR TABLE to recovers all the partitions > MSCK REPAIR TABLE t1; -- SELECT * FROM t1 returns results > SELECT * FROM t1; name age ------- --- Michael 20 Justin 19 Andy 30