ZooKeeper
ZooKeeper (see http://zookeeper.apache.org/) is a centralized service for configuration management and the synchronization of various aspects of naming and coordination. It manages a naming registry and effectively implements a system for managing the various statically and dynamically named objects in a hierarchical system. It also enables coordination and control to the shared resources, such as files and data, which are manipulated by multiple concurrent processes.
Unlike RDBMS, Hive does not natively support concurrency access and locking mechanisms. Hive relies on ZooKeeper for locking the shared resources since Hive 0.7.0. There are two types of locks provided by Hive through Zookeeper and they are as follows:
Shared lock: This is acquired when a table/partition is read. The concurrent shared locks are allowed in Hive.
Exclusive lock: This is acquired for all other operations that modify the table. For partition tables, only a shared lock is acquired if the change is only...
