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| <!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd"> |
| <concept id="impala_ha"> |
| <title>Configuring Impala for High Availability</title> |
| <prolog> |
| <metadata> |
| <data name="Category" value="Impala"/> |
| <data name="Category" value="Administrators"/> |
| <data name="Category" value="High Availability"/> |
| <data name="Category" value="Configuring"/> |
| <data name="Category" value="Data Analysts"/> |
| </metadata> |
| </prolog> |
| <conbody> |
| <p>The Impala StateStore checks on the health of all Impala daemons in a cluster, and |
| continuously relays its findings to each of the daemons. The Catalog stores metadata of |
| databases, tables, partitions, resource usage information, configuration settings, and other |
| objects managed by Impala. If StateStore and Catalog daemons are single instances in an Impala |
| cluster, it will create a single point of failure. Although Impala coordinators/executors |
| continue to execute queries if the StateStore node is down, coordinators/executors will not |
| get state updates. This causes degradation of admission control & cluster membership |
| updates. To mitigate this, a pair of StateStore and Catalog instances can be deployed in an |
| Impala cluster so that Impala cluster could survive failures of StateStore or Catalog.</p> |
| <p><b>Prerequisite:</b></p> |
| <p>To enable High Availability for Impala CatalogD and StateStore, you must configure at least |
| two Impala CatalogD, two StateStore instances on two different nodes.<note |
| id="note_dg1_qhh_fcc" type="note">CatalogD HA and Statestore HA are independent features. |
| Users can enable CatalogD HA, Statestore HA, or both CatalogD HA and Statestore |
| HA.</note></p> |
| <p outputclass="toc"/> |
| </conbody> |
| </concept> |