Introduce custom path and scan providers.

This allows extension modules to define their own methods for
scanning a relation, and get the core code to use them.  It's
unclear as yet how much use this capability will find, but we
won't find out if we never commit it.

KaiGai Kohei, reviewed at various times and in various levels
of detail by Shigeru Hanada, Tom Lane, Andres Freund, Álvaro
Herrera, and myself.

1 files changed, 9 insertions, 0 deletions

diff --git a/src/include/optimizer/pathnode.h b/src/include/optimizer/pathnode.h
index 26b17f5f7af..2b67ae6187b 100644
--- a/src/include/optimizer/pathnode.h
+++ b/src/include/optimizer/pathnode.h
@@ -129,6 +129,15 @@ extern Path *reparameterize_path(PlannerInfo *root, Path *path,
 					double loop_count);
 
 /*
+ * Interface definition of custom-scan providers
+ */
+extern void register_custom_path_provider(CustomPathMethods *cpp_methods);
+
+extern void create_customscan_paths(PlannerInfo *root,
+									RelOptInfo *baserel,
+									RangeTblEntry *rte);
+
+/*
  * prototypes for relnode.c
  */
 extern void setup_simple_rel_arrays(PlannerInfo *root);