Making HdfsPartition immutable has several benefits:
- HdfsPartition meta can be shared across table versions, which means in the legacy catalog update mode, catalog update can ignore unchanged partitions (IMPALA-3234) and send the update in partition granularity.
- Aborted DDL/DMLs won’t leave partition metadata in illegal states (
IMPALA-8406), which requires invalidation to recover.
- LocalCatalog coordinators can cache partition meta using the partition id as the key. When table version updates, only metadata of changed partitions needs to be reloaded (
- In the work of
IMPALA-3127, we don't need to assign a catalog version to partitions since the partition ids already identify the partitions.