June 2018
Beginner to intermediate
210 pages
5h 12m
English
Content preview from Apache Hive Essentials - Second Edition
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Locks
Locks ensure data isolation as described in the ACID principle. Hive has supported concurrency access and locking mechanisms since v0.7.0 and updated to a new lock manager in v0.13.0. There are two types of lock provided as follows:
- Shared lock: Also called S lock, it allows being shared concurrently. This is acquired when a table/partition is read.
- Exclusive lock: Also called X lock. This is acquired for all other operations that modify the table/partition.
For partition tables, only a shared lock is acquired if the change is only applicable to the newly-created partitions. An exclusive lock is acquired on the table if the change is applicable to all partitions. In addition, an exclusive lock on the table globally affects all partitions. ...
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