I was working in production and had to deploy into a partitioned table with 800 partitions, adding a new partition daily. The table is huge. I need to take a backup of the stable data. How would I do that using INSERT OVERWRITE into a copy table?

To back up a very large partitioned table in production, you can use a combination of Hive/Impala INSERT OVERWRITE and HDFS snapshots. First, create a new table that mirrors the schema of the source but is empty. Then run an INSERT OVERWRITE TABLE backup_table PARTITION (partition_col) SELECT * FROM source_table WHERE partition_col = 'stable_partition'; This copies only the stable partitions you need. If you want a full snapshot, use HDFS snapshotting: enable snapshots on the HDFS directory that stores the table, then take a snapshot before the deployment. This gives you a point‑in‑time copy without copying data. For incremental backups, you can use the Hive MERGE statement or a CDC tool to capture changes since the last backup. Finally, schedule the backup job to run during low‑traffic windows and verify the backup by running a quick count or checksum against the source.