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35th chunk of `doc/src/sgml/spi.sgml`
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</synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   <function>SPI_unregister_relation</function> removes an ephemeral named
   relation from the registry for the current connection.
  </para>
 </refsect1>

 <refsect1>
  <title>Arguments</title>

  <variablelist>
   <varlistentry>
    <term><literal>const char * <parameter>name</parameter></literal></term>
    <listitem>
     <para>
      the relation registry entry name
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1>
  <title>Return Value</title>

  <para>
   If the execution of the command was successful then the following
   (nonnegative) value will be returned:

   <variablelist>
    <varlistentry>
     <term><symbol>SPI_OK_REL_UNREGISTER</symbol></term>
     <listitem>
      <para>
       if the tuplestore has been successfully removed from the registry
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>

  <para>
   On error, one of the following negative values is returned:

   <variablelist>
    <varlistentry>
     <term><symbol>SPI_ERROR_ARGUMENT</symbol></term>
     <listitem>
      <para>
       if <parameter>name</parameter> is <symbol>NULL</symbol>
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><symbol>SPI_ERROR_UNCONNECTED</symbol></term>
     <listitem>
      <para>
       if called from an unconnected C function
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><symbol>SPI_ERROR_REL_NOT_FOUND</symbol></term>
     <listitem>
      <para>
       if <parameter>name</parameter> is not found in the registry for the
       current connection
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>
</refentry>

<!-- *********************************************** -->

<refentry id="spi-spi-register-trigger-data">
 <indexterm><primary>SPI_register_trigger_data</primary></indexterm>

 <indexterm>
  <primary>ephemeral named relation</primary>
  <secondary>registering with SPI</secondary>
 </indexterm>

 <indexterm>
  <primary>transition tables</primary>
  <secondary>implementation in PLs</secondary>
 </indexterm>

 <refmeta>
  <refentrytitle>SPI_register_trigger_data</refentrytitle>
  <manvolnum>3</manvolnum>
 </refmeta>

 <refnamediv>
  <refname>SPI_register_trigger_data</refname>
  <refpurpose>make ephemeral trigger data available in SPI queries</refpurpose>
 </refnamediv>

 <refsynopsisdiv>
<synopsis>
int SPI_register_trigger_data(TriggerData *<parameter>tdata</parameter>)
</synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   <function>SPI_register_trigger_data</function> makes any ephemeral
   relations captured by a trigger available to queries planned and executed
   through the current SPI connection.  Currently, this means the transition
   tables captured by an <literal>AFTER</literal> trigger defined with a
   <literal>REFERENCING OLD/NEW TABLE AS</literal> ... clause.  This function
   should be called by a PL trigger handler function after connecting.
  </para>
 </refsect1>

 <refsect1>
  <title>Arguments</title>

  <variablelist>
   <varlistentry>
    <term><literal>TriggerData *<parameter>tdata</parameter></literal></term>
    <listitem>
     <para>
       the <structname>TriggerData</structname> object passed to a trigger
       handler function as <literal>fcinfo->context</literal>
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1>
  <title>Return Value</title>

  <para>
   If the execution of the command was successful then the following
   (nonnegative) value will be returned:

   <variablelist>
    <varlistentry>
     <term><symbol>SPI_OK_TD_REGISTER</symbol></term>
     <listitem>
      <para>
       if the captured trigger data (if any) has been successfully registered
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>

  <para>
   On error, one
Title: SPI_unregister_relation and SPI_register_trigger_data: Removing Relations and Registering Trigger Data
Summary
This section details `SPI_unregister_relation`, which removes an ephemeral named relation from the current connection's registry, and `SPI_register_trigger_data`, which makes ephemeral relations captured by a trigger, such as transition tables from AFTER triggers with REFERENCING OLD/NEW TABLE clauses, available to queries executed through the current SPI connection. It should be called by a PL trigger handler function after connecting. Both functions return success or error codes.