docs/topics/impala_parquet_read_page_index.xml

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

  <title>PARQUET_READ_PAGE_INDEX Query Option</title>

  <titlealts audience="PDF">

    <navtitle>PARQUET_READ_PAGE_INDEX</navtitle>

  </titlealts>

  <prolog>
    <metadata>
      <data name="Category" value="Impala"/>
      <data name="Category" value="Impala Query Options"/>
      <data name="Category" value="Parquet"/>
      <data name="Category" value="Developers"/>
      <data name="Category" value="Data Analysts"/>
    </metadata>
  </prolog>

  <conbody>

    <p>
      Use the <codeph>PARQUET_READ_PAGE_INDEX</codeph> query option to disable or enable using
      the Parquet page index during scans. The page index contains min/max statistics at the
      page-level granularity. It can be used to skip pages and rows that do not match the
      conditions in the <codeph>WHERE</codeph> clause.
    </p>

    <p>
      This option enables the same optimization as the <codeph>PARQUET_READ_STATISTICS</codeph>
      at the finer grained page level.
    </p>

    <p>
      Impala supports filtering based on Parquet statistics:
    </p>

    <ul>
      <li>
        Of the types: Boolean, Integer, Decimal, String, Timestamp
      </li>

      <li>
        For simple predicates of the forms: <codeph>&lt;slot> &lt;op> &lt;constant></codeph> or
        <codeph>&lt;constant> &lt;op> &lt;slot></codeph>, where <codeph>&lt;op></codeph> is LT,
        LE, GE, GT, and EQ
      </li>
    </ul>

    <p>
      The supported values for the query option are:
      <ul>
        <li>
          <codeph>true</codeph> (<codeph>1</codeph>): Read the page-level statistics from the
          Parquet page index during query processing and filter out pages based on the
          statistics.
        </li>

        <li>
          <codeph>false</codeph> (<codeph>0</codeph>): Do not use the Parquet page index.
        </li>

        <li>
          Any other values are treated as <codeph>false</codeph>.
        </li>
      </ul>
    </p>

    <p>
      <b>Type:</b> Boolean
    </p>

    <p>
      <b>Default:</b> <codeph>TRUE</codeph>
    </p>

  </conbody>

</concept>