docs/topics/impala_parquet_fallback_schema_resolution.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_fallback_schema_resolution" rev="2.6.0 IMPALA-2835">

  <title>PARQUET_FALLBACK_SCHEMA_RESOLUTION Query Option (<keyword keyref="impala26"/> or higher only)</title>
  <titlealts audience="PDF"><navtitle>PARQUET_FALLBACK_SCHEMA_RESOLUTION</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="Schemas"/>
      <data name="Category" value="Developers"/>
      <data name="Category" value="Data Analysts"/>
    </metadata>
  </prolog>

  <conbody>

    <p rev="2.6.0 IMPALA-2835">
      <indexterm audience="hidden">PARQUET_FALLBACK_SCHEMA_RESOLUTION query option</indexterm>
      The <codeph>PARQUET_FALLBACK_SCHEMA_RESOLUTION</codeph> query option allows Impala to look
      up columns within Parquet files by column name, rather than column order,
      when necessary.
      The allowed values are:
      <ul>
        <li>
          POSITION (0)
        </li>
        <li>
          NAME (1)
        </li>
      </ul>
    </p>

    <p conref="../shared/impala_common.xml#common/usage_notes_blurb"/>
    <p>
      By default, Impala looks up columns within a Parquet file based on
      the order of columns in the table.
      The <codeph>name</codeph> setting for this option enables behavior for
      Impala queries similar to the Hive setting <codeph>parquet.column.index access=false</codeph>.
      It also allows Impala to query Parquet files created by Hive with the
      <codeph>parquet.column.index.access=false</codeph> setting in effect.
    </p>

    <p>
      <b>Type:</b> integer or string
    </p>

    <p conref="../shared/impala_common.xml#common/added_in_260"/>

    <p conref="../shared/impala_common.xml#common/related_info"/>
    <p>
      <xref href="impala_parquet.xml#parquet_schema_evolution"/>
    </p>

  </conbody>
</concept>