Sushanth Sowmyan created HIVE-7973:
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Summary: Hive Replication Support
Key: HIVE-7973
URL: https://issues.apache.org/jira/browse/HIVE-7973
Project: Hive
Issue Type: Bug
Components: Import/Export
Reporter: Sushanth Sowmyan
A need for replication is a common one in many database management systems, and
it's important for hive to evolve support for such a tool as part of its
ecosystem. Hive already supports an EXPORT and IMPORT command, which can be
used to dump out tables, distcp them to another cluster, and and import/create
from that. If we had a mechanism by which exports and imports could be
automated, it establishes the base with which replication can be developed.
One place where this kind of automation can be developed is with aid of the
HiveMetaStoreEventHandler mechanisms, to generate notifications when certain
changes are committed to the metastore, and then translate those notifications
to export actions, distcp actions and import actions on another import action.
Part of that already exists is with the Notification system that is part of
hcatalog-server-extensions. Initially, this was developed to be able to trigger
a JMS notification, which an Oozie workflow can use to can start off actions
keyed on the finishing of a job that used HCatalog to write to a table. While
this currently lives under hcatalog, the primary reason for its existence has a
scope well past hcatalog alone, and can be used as-is without the use of
HCatalog IF/OF. This can be extended, with the help of a library which does
that aforementioned translation. I also think that these sections should live
in a core hive module, rather than being tucked away inside hcatalog.
Once we have rudimentary support for table & partition replication, we can then
move on to further requirements of replication, such as metadata replications
(such as replication of changes to roles/etc), and/or optimize away the
requirement to distcp and use webhdfs instead, etc.
This Story tracks all the bits that go into development of such a system - I'll
create multiple smaller tasks inside this as we go on.
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