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/*-------------------------------------------------------------------------
*
* fdwapi.h
* API for foreign-data wrappers
*
* Copyright (c) 2010-2011, 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;
/*
* FdwPlan is the information returned to the planner by PlanForeignScan.
*/
typedef struct FdwPlan
{
NodeTag type;
/*
* Cost estimation info. The startup_cost is time before retrieving the
* first row, so it should include costs of connecting to the remote host,
* sending over the query, etc. Note that PlanForeignScan also ought to
* set baserel->rows and baserel->width if it can produce any usable
* estimates of those values.
*/
Cost startup_cost; /* cost expended before fetching any tuples */
Cost total_cost; /* total cost (assuming all tuples fetched) */
/*
* FDW private data, which will be available at execution time.
*
* Note that everything in this list must be copiable by copyObject(). One
* way to store an arbitrary blob of bytes is to represent it as a bytea
* Const. Usually, though, you'll be better off choosing a representation
* that can be dumped usefully by nodeToString().
*/
List *fdw_private;
} FdwPlan;
/*
* Callback function signatures --- see fdwhandler.sgml for more info.
*/
typedef FdwPlan *(*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 */
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