foreign.h

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/*-------------------------------------------------------------------------
 *
 * foreign.h
 *    support for foreign-data wrappers, servers and user mappings.
 *
 *
 * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
 *
 * src/include/foreign/foreign.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef FOREIGN_H
#define FOREIGN_H
 
#include "nodes/parsenodes.h"
 
 
/* Helper for obtaining username for user mapping */
#define MappingUserName(userid) \
    (OidIsValid(userid) ? GetUserNameFromId(userid, false) : "public")
 
 
typedef struct ForeignDataWrapper
{
    Oid         fdwid;          /* FDW Oid */
    Oid         owner;          /* FDW owner user Oid */
    char       *fdwname;        /* Name of the FDW */
    Oid         fdwhandler;     /* Oid of handler function, or 0 */
    Oid         fdwvalidator;   /* Oid of validator function, or 0 */
    Oid         fdwconnection;  /* Oid of connection string function, or 0 */
    List       *options;        /* fdwoptions as DefElem list */
} ForeignDataWrapper;
 
typedef struct ForeignServer
{
    Oid         serverid;       /* server Oid */
    Oid         fdwid;          /* foreign-data wrapper */
    Oid         owner;          /* server owner user Oid */
    char       *servername;     /* name of the server */
    char       *servertype;     /* server type, optional */
    char       *serverversion;  /* server version, optional */
    List       *options;        /* srvoptions as DefElem list */
} ForeignServer;
 
typedef struct UserMapping
{
    Oid         umid;           /* Oid of user mapping */
    Oid         userid;         /* local user Oid */
    Oid         serverid;       /* server Oid */
    List       *options;        /* useoptions as DefElem list */
} UserMapping;
 
typedef struct ForeignTable
{
    Oid         relid;          /* relation Oid */
    Oid         serverid;       /* server Oid */
    List       *options;        /* ftoptions as DefElem list */
} ForeignTable;
 
/* Flags for GetForeignServerExtended */
#define FSV_MISSING_OK  0x01
 
/* Flags for GetForeignDataWrapperExtended */
#define FDW_MISSING_OK  0x01
 
 
extern ForeignServer *GetForeignServer(Oid serverid);
extern char *ForeignServerName(Oid serverid);
extern ForeignServer *GetForeignServerExtended(Oid serverid,
                                               bits16 flags);
extern ForeignServer *GetForeignServerByName(const char *srvname,
                                             bool missing_ok);
extern char *ForeignServerConnectionString(Oid userid, Oid serverid);
extern UserMapping *GetUserMapping(Oid userid, Oid serverid);
extern ForeignDataWrapper *GetForeignDataWrapper(Oid fdwid);
extern ForeignDataWrapper *GetForeignDataWrapperExtended(Oid fdwid,
                                                         bits16 flags);
extern ForeignDataWrapper *GetForeignDataWrapperByName(const char *fdwname,
                                                       bool missing_ok);
extern ForeignTable *GetForeignTable(Oid relid);
 
extern List *GetForeignColumnOptions(Oid relid, AttrNumber attnum);
 
extern Oid  get_foreign_data_wrapper_oid(const char *fdwname, bool missing_ok);
extern Oid  get_foreign_server_oid(const char *servername, bool missing_ok);
 
#endif                          /* FOREIGN_H */