docs/topics/impala_resource_trace_ratio.xml

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<!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept rev="3.2.0" id="resource_trace_ratio">

  <title>RESOURCE_TRACE_RATIO Query Option (<keyword keyref="impala32_full"/> or higher only)</title>

  <titlealts audience="PDF">

    <navtitle>RESOURCE_TRACE_RATIO</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>
      The <codeph>RESOURCE_TRACE_RATIO</codeph> query option specifies the ratio of queries
      where the CPU usage info will be included in the profiles. Collecting CPU usage and
      sending it around adds a slight overhead during query execution. This query option lets
      you control whether to collect additional information to diagnose the resource usage.
    </p>

    <p>
      For example, setting <codeph>RESOURCE_TRACE_RATIO=1</codeph> adds a trace of the CPU usage
      to the profile of each query.
    </p>

    <p>
      Setting <codeph>RESOURCE_TRACE_RATIO=0.5</codeph> means that randomly selected half of all
      queries will have that information collected by the coordinator and included in the
      profiles.
    </p>

    <p>
      Setting <codeph>RESOURCE_TRACE_RATIO=0</codeph> means that CPU usage will not be tracked
      and included in the profiles.
    </p>

    <p>
      Values from 0 to 1 are allowed.
    </p>

    <p>
      <b>Type:</b> Number
    </p>

    <p>
      <b>Default:</b> 0
    </p>

    <p>
      <b>Added in:</b> <keyword keyref="impala32"/>
    </p>

  </conbody>

</concept>