docs/topics/impala_max_mem_estimate_for_admission.xml

<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept id="max_mem_estimate_for_admission">

  <title>MAX_MEM_ESTIMATE_FOR_ADMISSION Query Option</title>

  <titlealts audience="PDF">

    <navtitle>MAX_MEM_ESTIMATE_FOR_ADMISSION</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="Data Analysts"/>
    </metadata>
  </prolog>

  <conbody>

    <p>
      Use the <codeph>MAX_MEM_ESTIMATE_FOR_ADMISSION</codeph> query option to set an upper limit
      on the memory estimates of a query as a workaround for over-estimates precluding a query
      from being admitted.
    </p>

    <p>
      The query option takes effect when all of the below conditions are met:
    </p>

    <ul>
      <li>
        Memory-based admission control is enabled for the pool.
      </li>

      <li>
        The <codeph>MEM_LIMIT</codeph> query option is not set at the query, session, resource
        pool, or global level.
      </li>
    </ul>

    <p>
      When the above conditions are met, MIN(<codeph>MAX_MEM_ESTIMATE_FOR_ADMISSION</codeph>,
      mem_estimate) is used for admission control.
    </p>

    <p>
      Setting the <codeph>MEM_LIMIT</codeph> query option is usually a better option. Use the
      <codeph>MAX_MEM_ESTIMATE_FOR_ADMISSION</codeph> query option when it is not feasible to
      set <codeph>MEM_LIMIT</codeph> for each individual query.
    </p>

    <p conref="../shared/impala_common.xml#common/type_integer"/>

    <p conref="../shared/impala_common.xml#common/default_blurb"/>

    <p>
      <b>Added in:</b> <keyword keyref="impala31"/>
    </p>

    <p conref="../shared/impala_common.xml#common/usage_notes_blurb"/>

    <p conref="../shared/impala_common.xml#common/related_info"/>

  </conbody>

</concept>