fdwapi.h

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/*-------------------------------------------------------------------------
 *
 * fdwapi.h
 *    API for foreign-data wrappers
 *
 * Copyright (c) 2010-2026, PostgreSQL Global Development Group
 *
 * src/include/foreign/fdwapi.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef FDWAPI_H
#define FDWAPI_H
 
#include "access/parallel.h"
#include "nodes/execnodes.h"
#include "nodes/pathnodes.h"
 
/* avoid including explain_state.h here */
typedef struct ExplainState 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,
                                                 Plan *outer_plan);
 
typedef void (*BeginForeignScan_function) (ForeignScanState *node,
                                           int eflags);
 
typedef TupleTableSlot *(*IterateForeignScan_function) (ForeignScanState *node);
 
typedef bool (*RecheckForeignScan_function) (ForeignScanState *node,
                                             TupleTableSlot *slot);
 
typedef void (*ReScanForeignScan_function) (ForeignScanState *node);
 
typedef void (*EndForeignScan_function) (ForeignScanState *node);
 
typedef void (*GetForeignJoinPaths_function) (PlannerInfo *root,
                                              RelOptInfo *joinrel,
                                              RelOptInfo *outerrel,
                                              RelOptInfo *innerrel,
                                              JoinType jointype,
                                              JoinPathExtraData *extra);
 
typedef void (*GetForeignUpperPaths_function) (PlannerInfo *root,
                                               UpperRelationKind stage,
                                               RelOptInfo *input_rel,
                                               RelOptInfo *output_rel,
                                               void *extra);
 
typedef void (*AddForeignUpdateTargets_function) (PlannerInfo *root,
                                                  Index rtindex,
                                                  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 **(*ExecForeignBatchInsert_function) (EState *estate,
                                                             ResultRelInfo *rinfo,
                                                             TupleTableSlot **slots,
                                                             TupleTableSlot **planSlots,
                                                             int *numSlots);
 
typedef int (*GetForeignModifyBatchSize_function) (ResultRelInfo *rinfo);
 
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 (*BeginForeignInsert_function) (ModifyTableState *mtstate,
                                             ResultRelInfo *rinfo);
 
typedef void (*EndForeignInsert_function) (EState *estate,
                                           ResultRelInfo *rinfo);
 
typedef int (*IsForeignRelUpdatable_function) (Relation rel);
 
typedef bool (*PlanDirectModify_function) (PlannerInfo *root,
                                           ModifyTable *plan,
                                           Index resultRelation,
                                           int subplan_index);
 
typedef void (*BeginDirectModify_function) (ForeignScanState *node,
                                            int eflags);
 
typedef TupleTableSlot *(*IterateDirectModify_function) (ForeignScanState *node);
 
typedef void (*EndDirectModify_function) (ForeignScanState *node);
 
typedef RowMarkType (*GetForeignRowMarkType_function) (RangeTblEntry *rte,
                                                       LockClauseStrength strength);
 
typedef void (*RefetchForeignRow_function) (EState *estate,
                                            ExecRowMark *erm,
                                            Datum rowid,
                                            TupleTableSlot *slot,
                                            bool *updated);
 
typedef void (*ExplainForeignScan_function) (ForeignScanState *node,
                                             ExplainState *es);
 
typedef void (*ExplainForeignModify_function) (ModifyTableState *mtstate,
                                               ResultRelInfo *rinfo,
                                               List *fdw_private,
                                               int subplan_index,
                                               ExplainState *es);
 
typedef void (*ExplainDirectModify_function) (ForeignScanState *node,
                                              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);
 
typedef bool (*ImportForeignStatistics_function) (Relation relation,
                                                  List *va_cols,
                                                  int elevel);
 
typedef List *(*ImportForeignSchema_function) (ImportForeignSchemaStmt *stmt,
                                               Oid serverOid);
 
typedef void (*ExecForeignTruncate_function) (List *rels,
                                              DropBehavior behavior,
                                              bool restart_seqs);
 
typedef Size (*EstimateDSMForeignScan_function) (ForeignScanState *node,
                                                 ParallelContext *pcxt);
typedef void (*InitializeDSMForeignScan_function) (ForeignScanState *node,
                                                   ParallelContext *pcxt,
                                                   void *coordinate);
typedef void (*ReInitializeDSMForeignScan_function) (ForeignScanState *node,
                                                     ParallelContext *pcxt,
                                                     void *coordinate);
typedef void (*InitializeWorkerForeignScan_function) (ForeignScanState *node,
                                                      shm_toc *toc,
                                                      void *coordinate);
typedef void (*ShutdownForeignScan_function) (ForeignScanState *node);
typedef bool (*IsForeignScanParallelSafe_function) (PlannerInfo *root,
                                                    RelOptInfo *rel,
                                                    RangeTblEntry *rte);
typedef List *(*ReparameterizeForeignPathByChild_function) (PlannerInfo *root,
                                                            List *fdw_private,
                                                            RelOptInfo *child_rel);
 
typedef bool (*IsForeignPathAsyncCapable_function) (ForeignPath *path);
 
typedef void (*ForeignAsyncRequest_function) (AsyncRequest *areq);
 
typedef void (*ForeignAsyncConfigureWait_function) (AsyncRequest *areq);
 
typedef void (*ForeignAsyncNotify_function) (AsyncRequest *areq);
 
/*
 * 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 remote-join planning */
    GetForeignJoinPaths_function GetForeignJoinPaths;
 
    /* Functions for remote upper-relation (post scan/join) planning */
    GetForeignUpperPaths_function GetForeignUpperPaths;
 
    /* Functions for updating foreign tables */
    AddForeignUpdateTargets_function AddForeignUpdateTargets;
    PlanForeignModify_function PlanForeignModify;
    BeginForeignModify_function BeginForeignModify;
    ExecForeignInsert_function ExecForeignInsert;
    ExecForeignBatchInsert_function ExecForeignBatchInsert;
    GetForeignModifyBatchSize_function GetForeignModifyBatchSize;
    ExecForeignUpdate_function ExecForeignUpdate;
    ExecForeignDelete_function ExecForeignDelete;
    EndForeignModify_function EndForeignModify;
    BeginForeignInsert_function BeginForeignInsert;
    EndForeignInsert_function EndForeignInsert;
    IsForeignRelUpdatable_function IsForeignRelUpdatable;
    PlanDirectModify_function PlanDirectModify;
    BeginDirectModify_function BeginDirectModify;
    IterateDirectModify_function IterateDirectModify;
    EndDirectModify_function EndDirectModify;
 
    /* Functions for SELECT FOR UPDATE/SHARE row locking */
    GetForeignRowMarkType_function GetForeignRowMarkType;
    RefetchForeignRow_function RefetchForeignRow;
    RecheckForeignScan_function RecheckForeignScan;
 
    /* Support functions for EXPLAIN */
    ExplainForeignScan_function ExplainForeignScan;
    ExplainForeignModify_function ExplainForeignModify;
    ExplainDirectModify_function ExplainDirectModify;
 
    /* Support functions for ANALYZE */
    AnalyzeForeignTable_function AnalyzeForeignTable;
    ImportForeignStatistics_function ImportForeignStatistics;
 
    /* Support functions for IMPORT FOREIGN SCHEMA */
    ImportForeignSchema_function ImportForeignSchema;
 
    /* Support functions for TRUNCATE */
    ExecForeignTruncate_function ExecForeignTruncate;
 
    /* Support functions for parallelism under Gather node */
    IsForeignScanParallelSafe_function IsForeignScanParallelSafe;
    EstimateDSMForeignScan_function EstimateDSMForeignScan;
    InitializeDSMForeignScan_function InitializeDSMForeignScan;
    ReInitializeDSMForeignScan_function ReInitializeDSMForeignScan;
    InitializeWorkerForeignScan_function InitializeWorkerForeignScan;
    ShutdownForeignScan_function ShutdownForeignScan;
 
    /* Support functions for path reparameterization. */
    ReparameterizeForeignPathByChild_function ReparameterizeForeignPathByChild;
 
    /* Support functions for asynchronous execution */
    IsForeignPathAsyncCapable_function IsForeignPathAsyncCapable;
    ForeignAsyncRequest_function ForeignAsyncRequest;
    ForeignAsyncConfigureWait_function ForeignAsyncConfigureWait;
    ForeignAsyncNotify_function ForeignAsyncNotify;
} FdwRoutine;
 
 
/* Functions in foreign/foreign.c */
extern FdwRoutine *GetFdwRoutine(Oid fdwhandler);
extern Oid  GetForeignServerIdByRelId(Oid relid);
extern FdwRoutine *GetFdwRoutineByServerId(Oid serverid);
extern FdwRoutine *GetFdwRoutineByRelId(Oid relid);
extern FdwRoutine *GetFdwRoutineForRelation(Relation relation, bool makecopy);
extern bool IsImportableForeignTable(const char *tablename,
                                     ImportForeignSchemaStmt *stmt);
extern Path *GetExistingLocalJoinPath(RelOptInfo *joinrel);
 
#endif                          /* FDWAPI_H */