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| author | Etsuro Fujita | 2023-08-03 08:45:09 +0000 |
|---|---|---|
| committer | Etsuro Fujita | 2023-08-03 08:45:09 +0000 |
| commit | 0a1ff1d724e8ef71e1d5e602930bec49f0a9053b (patch) | |
| tree | 1c37c2054351d6a610c5c3626ac0ab5524627ff4 | |
| parent | db395e2239a2a595e937c82f1a14d225f0d02a82 (diff) | |
Doc: update documentation for creating custom scan paths.
Commit f49842d1e added a new callback for custom scan paths, but missed
updating the documentation.
Back-patch to all supported branches.
Discussion: https://postgr.es/m/CAPmGK15ODkN%2B%3DhkBCufj1HBW0x5OTb65Xuy7ryXchMdiCMpx_g%40mail.gmail.com
| -rw-r--r-- | doc/src/sgml/custom-scan.sgml | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/doc/src/sgml/custom-scan.sgml b/doc/src/sgml/custom-scan.sgml index b8963a28eb1..4ea00748b42 100644 --- a/doc/src/sgml/custom-scan.sgml +++ b/doc/src/sgml/custom-scan.sgml @@ -83,7 +83,7 @@ typedef struct CustomPath 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, of which there is currently only one. + custom path methods, which are further detailed below. </para> <para> @@ -123,6 +123,23 @@ Plan *(*PlanCustomPath) (PlannerInfo *root, 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> |