postgres/src/include/foreign/fdwapi.h

/*-------------------------------------------------------------------------
 *
 * fdwapi.h
 *	  API for foreign-data wrappers
 *
 * Copyright (c) 2010-2012, PostgreSQL Global Development Group
 *
 * src/include/foreign/fdwapi.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef FDWAPI_H
#define FDWAPI_H

#include "nodes/execnodes.h"
#include "nodes/relation.h"

/* To avoid including explain.h here, reference ExplainState thus: */
struct ExplainState;


/*
 * Callback function signatures --- see fdwhandler.sgml for more info.
 */

typedef void (*PlanForeignScan_function) (Oid foreigntableid,
										  PlannerInfo *root,
										  RelOptInfo *baserel);

typedef void (*ExplainForeignScan_function) (ForeignScanState *node,
													struct ExplainState *es);

typedef void (*BeginForeignScan_function) (ForeignScanState *node,
													   int eflags);

typedef TupleTableSlot *(*IterateForeignScan_function) (ForeignScanState *node);

typedef void (*ReScanForeignScan_function) (ForeignScanState *node);

typedef void (*EndForeignScan_function) (ForeignScanState *node);


/*
 * FdwRoutine is the struct returned by a foreign-data wrapper's handler
 * function.  It provides pointers to the callback functions needed by the
 * planner and executor.
 *
 * Currently, all functions must be supplied.  Later there may be optional
 * additions.  It's recommended that the handler initialize the struct with
 * makeNode(FdwRoutine) so that all fields are set to zero.
 */
typedef struct FdwRoutine
{
	NodeTag		type;

	PlanForeignScan_function PlanForeignScan;
	ExplainForeignScan_function ExplainForeignScan;
	BeginForeignScan_function BeginForeignScan;
	IterateForeignScan_function IterateForeignScan;
	ReScanForeignScan_function ReScanForeignScan;
	EndForeignScan_function EndForeignScan;
} FdwRoutine;


/* Functions in foreign/foreign.c */
extern FdwRoutine *GetFdwRoutine(Oid fdwhandler);
extern FdwRoutine *GetFdwRoutineByRelId(Oid relid);

#endif   /* FDWAPI_H */