This will hold the deterministic ID for partitions.
Until all existing partitions have this value, this is optional/nullable.
The row ID still exists and is used as the main foreign key in the
parquet_file and skipped_compaction tables.
The hash_id has a unique index so that we can look up records based on
it (if it's available).
If the parquet file record has a partition_hash_id value, use that to
generate the object storage path instead of the partition_id.
Carol (Nichols || Goulding)
Dom Dwyer
Stuart Carnie