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.

2 files changed, 32 insertions, 1 deletions

diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index d167b496fce..a44b4cde0fa 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -16,6 +16,7 @@
 
 #include "executor/execdesc.h"
 #include "nodes/parsenodes.h"
+#include "nodes/relation.h"
 #include "utils/lockwaitpolicy.h"
 
 
@@ -103,7 +104,7 @@ extern PGDLLIMPORT ExecutorCheckPerms_hook_type ExecutorCheckPerms_hook;
 extern void ExecReScan(PlanState *node);
 extern void ExecMarkPos(PlanState *node);
 extern void ExecRestrPos(PlanState *node);
-extern bool ExecSupportsMarkRestore(NodeTag plantype);
+extern bool ExecSupportsMarkRestore(Path *pathnode);
 extern bool ExecSupportsBackwardScan(Plan *node);
 extern bool ExecMaterializesOutput(NodeTag plantype);
 
diff --git a/src/include/executor/nodeCustom.h b/src/include/executor/nodeCustom.h
new file mode 100644
index 00000000000..1736d48bfaf
--- /dev/null
+++ b/src/include/executor/nodeCustom.h
@@ -0,0 +1,30 @@
+/* ------------------------------------------------------------------------
+ *
+ * nodeCustom.h
+ *
+ * prototypes for CustomScan nodes
+ *
+ * Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * ------------------------------------------------------------------------
+ */
+#ifndef NODECUSTOM_H
+#define NODECUSTOM_H
+#include "nodes/plannodes.h"
+#include "nodes/execnodes.h"
+
+/*
+ * General executor code
+ */
+extern CustomScanState *ExecInitCustomScan(CustomScan *custom_scan,
+										   EState *estate, int eflags);
+extern TupleTableSlot *ExecCustomScan(CustomScanState *node);
+extern Node *MultiExecCustomScan(CustomScanState *node);
+extern void ExecEndCustomScan(CustomScanState *node);
+
+extern void ExecReScanCustomScan(CustomScanState *node);
+extern void ExecCustomMarkPos(CustomScanState *node);
+extern void ExecCustomRestrPos(CustomScanState *node);
+
+#endif	/* NODECUSTOM_H */