docs/topics/impala_retry_failed_queries.xml

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<!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept id="RETRY_FAILED_QUERIES" rev="2.10.0 IMPALA-3200">
  <title>RETRY_FAILED_QUERIES Query Option</title>
  <titlealts audience="PDF">
    <navtitle>RETRY_FAILED_QUERIES</navtitle>
  </titlealts>
  <prolog>
    <metadata>
      <data name="Category" value="Impala"/>
      <data name="Category" value="Impala Query Options"/>
      <data name="Category" value="Querying"/>
      <data name="Category" value="Developers"/>
      <data name="Category" value="Administrators"/>
    </metadata>
  </prolog>
  <conbody>
    <p>Use the <codeph>RETRY_FAILED_QUERIES</codeph> query option to control
      whether or not queries are transparently retried on cluster membership
      changes. </p>
    <p>Cluster membership changes typically occur when an impalad crashes, or if the node is
      blacklisted by the Impala Coordinator. If a SELECT query fails due to a cluster membership
      change, the Coordinator will cancel and unregister the running query and then launch a retry
      of the query. For example, if one of the executor nodes fails during query execution, the query
      fails but is transparently re-executed, either with the executor node immediately replaced, or
      with a temporarily reduced number of executor nodes. This feature supports retrying the
      entire query and NOT the individual query fragments. INSERT and DDL queries will NOT be
      retried.</p>
    <p>Note that query retry will be skipped if the query has returned any results to the client. To
      avoid this, enable <codeph>Result Spooling</codeph> and set the
        <codeph>spool_all_results_for_retries</codeph> query option.</p>
    <p><b>Type:</b>
      <codeph>BOOLEAN</codeph></p>
    <p><b>Default:</b>
      <codeph>TRUE</codeph></p>
    <p><b>Added in:</b>
      <keyword keyref="impala40"/></p>
    <p><b>Related information:</b>
      <xref href="impala_transparent_query_retries.xml"/></p>
  </conbody>
</concept>