Existing PostgreSQL databases need to be reindexed

    </para>

  </section>

  <section id="postgresql-reindex">

    <!-- stretch to buster-->

    <title>Existing PostgreSQL databases need to be reindexed</title>

    <para>

      When upgrading from stretch to buster, the glibc locale data is upgraded.

      Specifically, this changes how PostgreSQL sorts data in text indexes.

      To avoid corruption, such indexes need to be <literal>REINDEX</literal>ed

      immediately after upgrading the <literal>locales</literal> or

      <literal>locales-all</literal> packages, before putting back the database

      into production.

    </para>

    <para>

      Suggested command: <literal>sudo -u postgres reindexdb --all</literal>

    </para>

    <para>

      Alternatively, upgrade the databases to PostgreSQL 11 using

      <literal>pg_upgradecluster</literal>.

      (This uses <literal>pg_dump</literal> by default which will rebuild all

      indexes. Using <literal>-m upgrade</literal> or <literal>pg_upgrade</literal>

      is <emphasis>not</emphasis> safe because it preserves the now-wrong

      index ordering.)

    </para>

    <para>

      Refer to the <ulink url="https://wiki.postgresql.org/wiki/Locale_data_changes">PostgreSQL Wiki</ulink>

      for more information.

    </para>

  </section>

</section>

</chapter>

      <surname>Perrier</surname>

      <contrib>bubulle, Lenny installation</contrib>

    </author>,

    <author>

      <firstname>Christoph</firstname>

      <surname>Berg</surname>

      <contrib>PostgreSQL-specific issues</contrib>

    </author>,

    <author>

      <firstname>Daniel</firstname>

      <surname>Baumann</surname>