by <literal>nodeToString</literal>, so that debugging routines that attempt to

print the custom path will work as designed. <structfield>methods</structfield> must

point to a (usually statically allocated) object implementing the required

custom path methods,ofwhichthere is currently only one.

custom path methods, whichare further detailed below.

</para>

<para>

be a <literal>CustomScan</literal> object, which the callback must allocate and

initialize. See <xref linkend="custom-scan-plan"/> for more details.

</para>

<para>

<programlisting>

List *(*ReparameterizeCustomPathByChild) (PlannerInfo *root,

List *custom_private,

RelOptInfo *child_rel);

</programlisting>

This callback is called while converting a path parameterized by the

top-most parent of the given child relation <literal>child_rel</literal>

to be parameterized by the child relation. The callback is used to

reparameterize any paths or translate any expression nodes saved in the

given <literal>custom_private</literal> member of a

<structname>CustomPath</structname>. The callback may use

<literal>reparameterize_path_by_child</literal>,

<literal>adjust_appendrel_attrs</literal> or

<literal>adjust_appendrel_attrs_multilevel</literal> as required.

</para>

</sect2>

</sect1>