fdwapi.h

Go to the documentation of this file.

/*-------------------------------------------------------------------------
 *
 * fdwapi.h
 *    API for foreign-data wrappers
 *
 * Copyright (c) 2010-2013, 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 (*GetForeignRelSize_function) (PlannerInfo *root,
                                                        RelOptInfo *baserel,
                                                        Oid foreigntableid);

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

typedef ForeignScan *(*GetForeignPlan_function) (PlannerInfo *root,
                                                         RelOptInfo *baserel,
                                                          Oid foreigntableid,
                                                      ForeignPath *best_path,
                                                             List *tlist,
                                                         List *scan_clauses);

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);

typedef void (*AddForeignUpdateTargets_function) (Query *parsetree,
                                                   RangeTblEntry *target_rte,
                                                   Relation target_relation);

typedef List *(*PlanForeignModify_function) (PlannerInfo *root,
                                                         ModifyTable *plan,
                                                         Index resultRelation,
                                                         int subplan_index);

typedef void (*BeginForeignModify_function) (ModifyTableState *mtstate,
                                                         ResultRelInfo *rinfo,
                                                         List *fdw_private,
                                                         int subplan_index,
                                                         int eflags);

typedef TupleTableSlot *(*ExecForeignInsert_function) (EState *estate,
                                                        ResultRelInfo *rinfo,
                                                        TupleTableSlot *slot,
                                                   TupleTableSlot *planSlot);

typedef TupleTableSlot *(*ExecForeignUpdate_function) (EState *estate,
                                                        ResultRelInfo *rinfo,
                                                        TupleTableSlot *slot,
                                                   TupleTableSlot *planSlot);

typedef TupleTableSlot *(*ExecForeignDelete_function) (EState *estate,
                                                        ResultRelInfo *rinfo,
                                                        TupleTableSlot *slot,
                                                   TupleTableSlot *planSlot);

typedef void (*EndForeignModify_function) (EState *estate,
                                                       ResultRelInfo *rinfo);

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

typedef void (*ExplainForeignModify_function) (ModifyTableState *mtstate,
                                                        ResultRelInfo *rinfo,
                                                           List *fdw_private,
                                                           int subplan_index,
                                                    struct ExplainState *es);

typedef int (*AcquireSampleRowsFunc) (Relation relation, int elevel,
                                               HeapTuple *rows, int targrows,
                                                  double *totalrows,
                                                  double *totaldeadrows);

typedef bool (*AnalyzeForeignTable_function) (Relation relation,
                                                 AcquireSampleRowsFunc *func,
                                                    BlockNumber *totalpages);

/*
 * 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.
 *
 * More function pointers are likely to be added in the future.  Therefore
 * it's recommended that the handler initialize the struct with
 * makeNode(FdwRoutine) so that all fields are set to NULL.  This will
 * ensure that no fields are accidentally left undefined.
 */
typedef struct FdwRoutine
{
    NodeTag     type;

    /* Functions for scanning foreign tables */
    GetForeignRelSize_function GetForeignRelSize;
    GetForeignPaths_function GetForeignPaths;
    GetForeignPlan_function GetForeignPlan;
    BeginForeignScan_function BeginForeignScan;
    IterateForeignScan_function IterateForeignScan;
    ReScanForeignScan_function ReScanForeignScan;
    EndForeignScan_function EndForeignScan;

    /*
     * Remaining functions are optional.  Set the pointer to NULL for any that
     * are not provided.
     */

    /* Functions for updating foreign tables */
    AddForeignUpdateTargets_function AddForeignUpdateTargets;
    PlanForeignModify_function PlanForeignModify;
    BeginForeignModify_function BeginForeignModify;
    ExecForeignInsert_function ExecForeignInsert;
    ExecForeignUpdate_function ExecForeignUpdate;
    ExecForeignDelete_function ExecForeignDelete;
    EndForeignModify_function EndForeignModify;

    /* Support functions for EXPLAIN */
    ExplainForeignScan_function ExplainForeignScan;
    ExplainForeignModify_function ExplainForeignModify;

    /* Support functions for ANALYZE */
    AnalyzeForeignTable_function AnalyzeForeignTable;
} FdwRoutine;


/* Functions in foreign/foreign.c */
extern FdwRoutine *GetFdwRoutine(Oid fdwhandler);
extern FdwRoutine *GetFdwRoutineByRelId(Oid relid);
extern FdwRoutine *GetFdwRoutineForRelation(Relation relation, bool makecopy);

#endif   /* FDWAPI_H */