Help Center/ MapReduce Service/ Developer Guide (Normal_3.x)/ Impala Development Guide (Security Mode)/ Impala Application Development Overview/ Common Concepts of Impala Application Development
Updated on 2026-04-10 GMT+08:00
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Common Concepts of Impala Application Development

  • Client

    Users can access the server from the client through Java APIs and Thrift APIs to perform Impala-related operations. In this document, the Impala client refers to the Impala installation directory, which contains sample code for accessing Impala through Java APIs.

  • HiveQL

    Hive Query Language (SQL-like statement, similar to Hive)

  • Statestore

    The StateStore checks on the health of all Impalad instance in an Impala cluster, and continuously broadcasts its findings to each of those Impalad instances. If an Impalad instance goes offline due to node failures, network errors, or other reasons, the StateStore informs all the other Impalad instances so that future queries can avoid making requests to the unreachable Impalad instances.

  • Catalog

    The catalog service broadcasts any changed metadata from each Impalad instance to other Impalad instances in a cluster. The catalog service eliminates the need to manually issue the REFRESH statement on other nodes after metadata changes on a specific Impalad instance. To create or modify a table in Hive, you need to execute the REFRESH or INVALIDATE METADATA statements.