/* ----------------------------------------------------------------
* ExecInitForeignScan
* ----------------------------------------------------------------
*/
ForeignScanState *
ExecInitForeignScan(ForeignScan *node, EState *estate, int eflags)
{
ForeignScanState *scanstate;
Relation currentRelation;
FdwRoutine *fdwroutine;
/* check for unsupported flags */
Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
/*
* create state structure
*/
scanstate = makeNode(ForeignScanState);
scanstate->ss.ps.plan = (Plan *) node;
scanstate->ss.ps.state = estate;
/*
* Miscellaneous initialization
*
* create expression context for node
*/
ExecAssignExprContext(estate, &scanstate->ss.ps);
scanstate->ss.ps.ps_TupFromTlist = false;
/*
* initialize child expressions
*/
scanstate->ss.ps.targetlist = (List *)
ExecInitExpr((Expr *) node->scan.plan.targetlist,
(PlanState *) scanstate);
scanstate->ss.ps.qual = (List *)
ExecInitExpr((Expr *) node->scan.plan.qual,
(PlanState *) scanstate);
/*
* tuple table initialization
*/
ExecInitResultTupleSlot(estate, &scanstate->ss.ps);
ExecInitScanTupleSlot(estate, &scanstate->ss);
/*
* open the base relation and acquire appropriate lock on it.
*/
currentRelation = ExecOpenScanRelation(estate, node->scan.scanrelid);
scanstate->ss.ss_currentRelation = currentRelation;
/*
* get the scan type from the relation descriptor. (XXX at some point we
* might want to let the FDW editorialize on the scan tupdesc.)
*/
ExecAssignScanType(&scanstate->ss, RelationGetDescr(currentRelation));
/*
* Initialize result tuple type and projection info.
*/
ExecAssignResultTypeFromTL(&scanstate->ss.ps);
ExecAssignScanProjectionInfo(&scanstate->ss);
/*
* Acquire function pointers from the FDW's handler, and init fdw_state.
*/
fdwroutine = GetFdwRoutineForRelation(currentRelation, true);
scanstate->fdwroutine = fdwroutine;
scanstate->fdw_state = NULL;
/*
* Tell the FDW to initiate the scan.
*/
fdwroutine->BeginForeignScan(scanstate, eflags);
return scanstate;
}
/* ----------------------------------------------------------------
* ExecInitForeignScan
* ----------------------------------------------------------------
*/
ForeignScanState *
ExecInitForeignScan(ForeignScan *node, EState *estate, int eflags)
{
ForeignScanState *scanstate;
Relation currentRelation = NULL;
Index scanrelid = node->scan.scanrelid;
Index tlistvarno;
FdwRoutine *fdwroutine;
/* check for unsupported flags */
Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
/*
* create state structure
*/
scanstate = makeNode(ForeignScanState);
scanstate->ss.ps.plan = (Plan *) node;
scanstate->ss.ps.state = estate;
/*
* Miscellaneous initialization
*
* create expression context for node
*/
ExecAssignExprContext(estate, &scanstate->ss.ps);
scanstate->ss.ps.ps_TupFromTlist = false;
/*
* initialize child expressions
*/
scanstate->ss.ps.targetlist = (List *)
ExecInitExpr((Expr *) node->scan.plan.targetlist,
(PlanState *) scanstate);
scanstate->ss.ps.qual = (List *)
ExecInitExpr((Expr *) node->scan.plan.qual,
(PlanState *) scanstate);
scanstate->fdw_recheck_quals = (List *)
ExecInitExpr((Expr *) node->fdw_recheck_quals,
(PlanState *) scanstate);
/*
* tuple table initialization
*/
ExecInitResultTupleSlot(estate, &scanstate->ss.ps);
ExecInitScanTupleSlot(estate, &scanstate->ss);
/*
* open the base relation, if any, and acquire an appropriate lock on it;
* also acquire function pointers from the FDW's handler
*/
if (scanrelid > 0)
{
currentRelation = ExecOpenScanRelation(estate, scanrelid, eflags);
scanstate->ss.ss_currentRelation = currentRelation;
fdwroutine = GetFdwRoutineForRelation(currentRelation, true);
}
else
{
/* We can't use the relcache, so get fdwroutine the hard way */
fdwroutine = GetFdwRoutineByServerId(node->fs_server);
}
/*
* Determine the scan tuple type. If the FDW provided a targetlist
* describing the scan tuples, use that; else use base relation's rowtype.
*/
if (node->fdw_scan_tlist != NIL || currentRelation == NULL)
{
TupleDesc scan_tupdesc;
scan_tupdesc = ExecTypeFromTL(node->fdw_scan_tlist, false);
ExecAssignScanType(&scanstate->ss, scan_tupdesc);
/* Node's targetlist will contain Vars with varno = INDEX_VAR */
tlistvarno = INDEX_VAR;
}
else
{
ExecAssignScanType(&scanstate->ss, RelationGetDescr(currentRelation));
/* Node's targetlist will contain Vars with varno = scanrelid */
tlistvarno = scanrelid;
}
/*
* Initialize result tuple type and projection info.
*/
ExecAssignResultTypeFromTL(&scanstate->ss.ps);
ExecAssignScanProjectionInfoWithVarno(&scanstate->ss, tlistvarno);
/*
* Initialize FDW-related state.
*/
scanstate->fdwroutine = fdwroutine;
scanstate->fdw_state = NULL;
/* Initialize any outer plan. */
if (outerPlan(node))
outerPlanState(scanstate) =
ExecInitNode(outerPlan(node), estate, eflags);
/*
* Tell the FDW to initialize the scan.
*/
fdwroutine->BeginForeignScan(scanstate, eflags);
return scanstate;
}