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This commands displays information about currently running compaction and recent history (configurable retention period) of compactions. This history display is available since HIV-12353.
Transaction/Lock Manager
A new logical entity called "transaction manager" was added which incorporated previous notion of "database/table/partition lock manager" (hive.lock.manager with default of org.apache.hadoop.hive.ql.lockmgr.zookeeper.ZooKeeperHiveLockManager). The transaction manager has also been added to Hive, the DbLockManager. This lock manager stores all lock information in the metastore. In addition all transactions are stored in the metastore. This means that is now additionally responsible for managing of transactions locks. The default DummyTxnManager emulates behavior of old Hive versions: has no transactions and uses hive.lock.manager property to create lock manager for tables, partitions and databases. A newly added DbTxnManager manages all locks/transactions in Hive metastore with DbLockManager (transactions and locks are durable in the face of server failure. ). This means that previous behavior of locking in ZooKeeper is not present anymore when transactions are enabled. To avoid clients dying and leaving transaction or locks dangling, a heartbeat is sent from lock holders and transaction initiators to the metastore on a regular basis. If a heartbeat is not received in the configured amount of time, the lock or transaction will be aborted.
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