C++ ExecAssignExprContext函数代码示例

/* ----------------------------------------------------------------
 *		ExecInitSeqScan
 * ----------------------------------------------------------------
 */
SeqScanState *
ExecInitSeqScan(SeqScan *node, EState *estate, int eflags)
{
	SeqScanState *scanstate;
	AttrNumber ctid_attrno;

	/*
	 * Once upon a time it was possible to have an outerPlan of a SeqScan, but
	 * not any more.
	 */
	Assert(outerPlan(node) == NULL);
	Assert(innerPlan(node) == NULL);

	/*
	 * create state structure
	 */
	scanstate = makeNode(SeqScanState);
	scanstate->ps.plan = (Plan *) node;
	scanstate->ps.state = estate;

	/*
	 * Miscellaneous initialization
	 *
	 * create expression context for node
	 */
	ExecAssignExprContext(estate, &scanstate->ps);

	/*
	 * initialize child expressions
	 */
	scanstate->ps.targetlist = (List *)
		ExecInitExpr((Expr *) node->plan.targetlist,
					 (PlanState *) scanstate);
	scanstate->ps.qual = (List *)
		ExecInitExpr((Expr *) node->plan.qual,
					 (PlanState *) scanstate);

#define SEQSCAN_NSLOTS 2

	/*
	 * tuple table initialization
	 */
	ExecInitResultTupleSlot(estate, &scanstate->ps);
	ExecInitScanTupleSlot(estate, scanstate);

	/*
	 * initialize scan relation
	 */
	InitScanRelation(scanstate, estate);

	scanstate->ps.ps_TupFromTlist = false;

	/*
	 * Initialize result tuple type and projection info.
	 */
	ExecAssignResultTypeFromTL(&scanstate->ps);
	ExecAssignScanProjectionInfo(scanstate);

	return scanstate;
}

/* ----------------------------------------------------------------
 *		ExecInitWorkTableScan
 * ----------------------------------------------------------------
 */
WorkTableScanState *
ExecInitWorkTableScan(WorkTableScan *node, EState *estate, int eflags)
{
	WorkTableScanState *scanstate;

	/* check for unsupported flags */
	/*
	 * GPDB_84_MERGE_FIXME: Make sure we don't require EXEC_FLAG_BACKWARD
	 * in GPDB.
	 */
	Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));

	/*
	 * WorkTableScan should not have any children.
	 */
	Assert(outerPlan(node) == NULL);
	Assert(innerPlan(node) == NULL);

	/*
	 * create new WorkTableScanState for node
	 */
	scanstate = makeNode(WorkTableScanState);
	scanstate->ss.ps.plan = (Plan *) node;
	scanstate->ss.ps.state = estate;
	scanstate->rustate = NULL;	/* we'll set this later */

	/*
	 * Miscellaneous initialization
	 *
	 * create expression context for node
	 */
	ExecAssignExprContext(estate, &scanstate->ss.ps);

	/*
	 * 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);

#define WORKTABLESCAN_NSLOTS 2

	/*
	 * tuple table initialization
	 */
	ExecInitResultTupleSlot(estate, &scanstate->ss.ps);
	ExecInitScanTupleSlot(estate, &scanstate->ss);

	/*
	 * Initialize result tuple type, but not yet projection info.
	 */
	ExecAssignResultTypeFromTL(&scanstate->ss.ps);

	/* scanstate->ss.ps.ps_TupFromTlist = false; */

	return scanstate;
}

/* ----------------------------------------------------------------
 *		ExecInitAppendOnlyScan
 * ----------------------------------------------------------------
 */
AppendOnlyScanState *
ExecInitAppendOnlyScan(AppendOnlyScan *node, EState *estate, int eflags)
{
	AppendOnlyScanState	*appendonlystate;
	Relation			currentRelation;
	
	Assert(outerPlan(node) == NULL);
	Assert(innerPlan(node) == NULL);

	/*
	 * create state structure
	 */
	appendonlystate = makeNode(AppendOnlyScanState);
	appendonlystate->ss.ps.plan = (Plan *) node;
	appendonlystate->ss.ps.state = estate;

	/*
	 * Miscellaneous initialization
	 *
	 * create expression context for node
	 */
	ExecAssignExprContext(estate, &appendonlystate->ss.ps);

	/*
	 * initialize child expressions
	 */
	appendonlystate->ss.ps.targetlist = (List *)
		ExecInitExpr((Expr *) node->scan.plan.targetlist,
					 (PlanState *) appendonlystate);
	appendonlystate->ss.ps.qual = (List *)
		ExecInitExpr((Expr *) node->scan.plan.qual,
					 (PlanState *) appendonlystate);

#define AOSCAN_NSLOTS 2

	/*
	 * tuple table initialization
	 */
	ExecInitResultTupleSlot(estate, &appendonlystate->ss.ps);
	ExecInitScanTupleSlot(estate, &appendonlystate->ss);

	/*
	 * get the relation object id from the relid'th entry in the range table
	 * and open that relation.
	 */
	currentRelation = ExecOpenScanRelation(estate, node->scan.scanrelid);	
	appendonlystate->ss.ss_currentRelation = currentRelation;
	ExecAssignScanType(&appendonlystate->ss, RelationGetDescr(currentRelation));
	
	/*
	 * Initialize result tuple type and projection info.
	 */
	ExecAssignResultTypeFromTL(&appendonlystate->ss.ps);
	ExecAssignScanProjectionInfo(&appendonlystate->ss);

	initGpmonPktForAppendOnlyScan((Plan *)node, &appendonlystate->ss.ps.gpmon_pkt, estate);

	return appendonlystate;
}

/* ----------------------------------------------------------------
 *		ExecInitResult
 *
 *		Creates the run-time state information for the result node
 *		produced by the planner and initailizes outer relations
 *		(child nodes).
 * ----------------------------------------------------------------
 */
ResultState *
ExecInitResult(Result *node, EState *estate)
{
	ResultState *resstate;

	/*
	 * create state structure
	 */
	resstate = makeNode(ResultState);
	resstate->ps.plan = (Plan *) node;
	resstate->ps.state = estate;

	resstate->rs_done = false;
	resstate->rs_checkqual = (node->resconstantqual == NULL) ? false : true;

	/*
	 * Miscellaneous initialization
	 *
	 * create expression context for node
	 */
	ExecAssignExprContext(estate, &resstate->ps);

#define RESULT_NSLOTS 1

	/*
	 * tuple table initialization
	 */
	ExecInitResultTupleSlot(estate, &resstate->ps);

	/*
	 * initialize child expressions
	 */
	resstate->ps.targetlist = (List *)
		ExecInitExpr((Expr *) node->plan.targetlist,
					 (PlanState *) resstate);
	resstate->ps.qual = (List *)
		ExecInitExpr((Expr *) node->plan.qual,
					 (PlanState *) resstate);
	resstate->resconstantqual = ExecInitExpr((Expr *) node->resconstantqual,
											 (PlanState *) resstate);

	/*
	 * initialize child nodes
	 */
	outerPlanState(resstate) = ExecInitNode(outerPlan(node), estate);

	/*
	 * we don't use inner plan
	 */
	Assert(innerPlan(node) == NULL);

	/*
	 * initialize tuple type and projection info
	 */
	ExecAssignResultTypeFromTL(&resstate->ps);
	ExecAssignProjectionInfo(&resstate->ps);

	return resstate;
}

/* -----------------
 * ExecInitGroup
 *
 *	Creates the run-time information for the group node produced by the
 *	planner and initializes its outer subtree
 * -----------------
 */
GroupState *
ExecInitGroup(Group *node, EState *estate, int eflags)
{
	GroupState *grpstate;

	/* check for unsupported flags */
	Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));

	/*
	 * create state structure
	 */
	grpstate = makeNode(GroupState);
	grpstate->ss.ps.plan = (Plan *) node;
	grpstate->ss.ps.state = estate;
	grpstate->ss.ps.ExecProcNode = ExecGroup;
	grpstate->grp_done = false;

	/*
	 * create expression context
	 */
	ExecAssignExprContext(estate, &grpstate->ss.ps);

	/*
	 * tuple table initialization
	 */
	ExecInitScanTupleSlot(estate, &grpstate->ss);
	ExecInitResultTupleSlot(estate, &grpstate->ss.ps);

	/*
	 * initialize child expressions
	 */
	grpstate->ss.ps.qual =
		ExecInitQual(node->plan.qual, (PlanState *) grpstate);

	/*
	 * initialize child nodes
	 */
	outerPlanState(grpstate) = ExecInitNode(outerPlan(node), estate, eflags);

	/*
	 * initialize tuple type.
	 */
	ExecAssignScanTypeFromOuterPlan(&grpstate->ss);

	/*
	 * Initialize result tuple type and projection info.
	 */
	ExecAssignResultTypeFromTL(&grpstate->ss.ps);
	ExecAssignProjectionInfo(&grpstate->ss.ps, NULL);

	/*
	 * Precompute fmgr lookup data for inner loop
	 */
	grpstate->eqfunctions =
		execTuplesMatchPrepare(node->numCols,
							   node->grpOperators);

	return grpstate;
}

/* ----------------------------------------------------------------
 *		ExecInitLimit
 *
 *		This initializes the limit node state structures and
 *		the node's subplan.
 * ----------------------------------------------------------------
 */
LimitState *
ExecInitLimit(Limit *node, EState *estate, int eflags)
{
	LimitState *limitstate;
	Plan	   *outerPlan;

	/* check for unsupported flags */
	Assert(!(eflags & EXEC_FLAG_MARK));

	/*
	 * create state structure
	 */
	limitstate = makeNode(LimitState);
	limitstate->ps.plan = (Plan *) node;
	limitstate->ps.state = estate;

	limitstate->lstate = LIMIT_INITIAL;

	/*
	 * Miscellaneous initialization
	 *
	 * Limit nodes never call ExecQual or ExecProject, but they need an
	 * exprcontext anyway to evaluate the limit/offset parameters in.
	 */
	ExecAssignExprContext(estate, &limitstate->ps);

	/*
	 * initialize child expressions
	 */
	limitstate->limitOffset = ExecInitExpr((Expr *) node->limitOffset,
										   (PlanState *) limitstate);
	limitstate->limitCount = ExecInitExpr((Expr *) node->limitCount,
										  (PlanState *) limitstate);

#define LIMIT_NSLOTS 1

	/*
	 * Tuple table initialization (XXX not actually used...)
	 */
	ExecInitResultTupleSlot(estate, &limitstate->ps);

	/*
	 * then initialize outer plan
	 */
	outerPlan = outerPlan(node);
	outerPlanState(limitstate) = ExecInitNode(outerPlan, estate, eflags);

	/*
	 * limit nodes do no projections, so initialize projection info for this
	 * node appropriately
	 */
	ExecAssignResultTypeFromTL(&limitstate->ps);
	limitstate->ps.ps_ProjInfo = NULL;

	initGpmonPktForLimit((Plan *)node, &limitstate->ps.gpmon_pkt, estate);
	
	return limitstate;
}

/**
 * Init nodeDML, which initializes the insert TupleTableSlot.
 * */
DMLState*
ExecInitDML(DML *node, EState *estate, int eflags)
{
	
	/* check for unsupported flags */
	Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK | EXEC_FLAG_REWIND)));
	
	DMLState *dmlstate = makeNode(DMLState);
	dmlstate->ps.plan = (Plan *)node;
	dmlstate->ps.state = estate;

	ExecInitResultTupleSlot(estate, &dmlstate->ps);

	dmlstate->ps.targetlist = (List *)
						ExecInitExpr((Expr *) node->plan.targetlist,
						(PlanState *) dmlstate);

	Plan *outerPlan  = outerPlan(node);
	outerPlanState(dmlstate) = ExecInitNode(outerPlan, estate, eflags);

	ExecAssignResultTypeFromTL(&dmlstate->ps);

	/* Create expression evaluation context. This will be used for projections */
	ExecAssignExprContext(estate, &dmlstate->ps);

	/*
	 * Create projection info from the child tuple descriptor and our target list
	 * Projection will be placed in the ResultSlot
	 */
	TupleTableSlot *childResultSlot = outerPlanState(dmlstate)->ps_ResultTupleSlot;
	ExecAssignProjectionInfo(&dmlstate->ps, childResultSlot->tts_tupleDescriptor);
	
	/*
	 * Initialize slot to insert/delete using output relation descriptor.
	 */
	dmlstate->cleanedUpSlot = ExecInitExtraTupleSlot(estate);

	/*
	 * Both input and output of the junk filter include dropped attributes, so
	 * the junk filter doesn't need to do anything special there about them
	 */
	TupleDesc cleanTupType = CreateTupleDescCopy(dmlstate->ps.state->es_result_relation_info->ri_RelationDesc->rd_att); 
	dmlstate->junkfilter = ExecInitJunkFilter(node->plan.targetlist,
			cleanTupType,
			dmlstate->cleanedUpSlot);

	if (estate->es_instrument)
	{
	        dmlstate->ps.cdbexplainbuf = makeStringInfo();

	        /* Request a callback at end of query. */
	        dmlstate->ps.cdbexplainfun = ExecDMLExplainEnd;
	}

	initGpmonPktForDML((Plan *)node, &dmlstate->ps.gpmon_pkt, estate);
	
	return dmlstate;
}

/* ----------------------------------------------------------------
 *		ExecInitHash
 *
 *		Init routine for Hash node
 * ----------------------------------------------------------------
 */
HashState *
ExecInitHash(Hash *node, EState *estate, int eflags)
{
	HashState  *hashstate;

	/* check for unsupported flags */
	Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));

	/*
	 * create state structure
	 */
	hashstate = makeNode(HashState);
	hashstate->ps.plan = (Plan *) node;
	hashstate->ps.state = estate;
	hashstate->hashtable = NULL;
	hashstate->hashkeys = NIL;	/* will be set by parent HashJoin */

	/*CHANGED BY YASIN*/
	if (eflags & EXEC_FLAG_INAROUND) hashstate->ps.ps_InAround = true;

	/*
	 * Miscellaneous initialization
	 *
	 * create expression context for node
	 */
	ExecAssignExprContext(estate, &hashstate->ps);

#define HASH_NSLOTS 1

	/*
	 * initialize our result slot
	 */
	ExecInitResultTupleSlot(estate, &hashstate->ps);

	/*
	 * initialize child expressions
	 */
	hashstate->ps.targetlist = (List *)
		ExecInitExpr((Expr *) node->plan.targetlist,
					 (PlanState *) hashstate);
	hashstate->ps.qual = (List *)
		ExecInitExpr((Expr *) node->plan.qual,
					 (PlanState *) hashstate);

	/*
	 * initialize child nodes
	 */
	outerPlanState(hashstate) = ExecInitNode(outerPlan(node), estate, eflags);

	/*
	 * initialize tuple type. no need to initialize projection info because
	 * this node doesn't do projections
	 */
	ExecAssignResultTypeFromTL(&hashstate->ps);
	hashstate->ps.ps_ProjInfo = NULL;

	return hashstate;
}

/* ----------------------------------------------------------------
 *   	ExecInitHash
 *
 *   	Init routine for Hash node
 * ----------------------------------------------------------------
 */
bool
ExecInitHash(Hash *node, EState *estate, Plan *parent)
{
    HashState		*hashstate;
    Plan		*outerPlan;
    
    SO1_printf("ExecInitHash: %s\n",
	       "initializing hash node");
    
    /* ----------------
     *  assign the node's execution state
     * ----------------
     */
    node->plan.state = estate;
    
    /* ----------------
     * create state structure
     * ----------------
     */
    hashstate = makeNode(HashState);
    node->hashstate = hashstate;
    hashstate->hashBatches = NULL;
    
    /* ----------------
     *  Miscellanious initialization
     *
     *	     +	assign node's base_id
     *       +	assign debugging hooks and
     *       +	create expression context for node
     * ----------------
     */
    ExecAssignNodeBaseInfo(estate, &hashstate->cstate, parent);
    ExecAssignExprContext(estate, &hashstate->cstate);
    
#define HASH_NSLOTS 1
    /* ----------------
     * initialize our result slot
     * ----------------
     */
    ExecInitResultTupleSlot(estate, &hashstate->cstate);
    
    /* ----------------
     * initializes child nodes
     * ----------------
     */
    outerPlan = outerPlan(node);
    ExecInitNode(outerPlan, estate, (Plan *)node);
    
    /* ----------------
     * 	initialize tuple type. no need to initialize projection
     *  info because this node doesn't do projections
     * ----------------
     */
    ExecAssignResultTypeFromOuterPlan((Plan *) node, &hashstate->cstate);
    hashstate->cstate.cs_ProjInfo = NULL;
    
    return TRUE;
}

/* ----------------------------------------------------------------
 *		ExecInitLimit
 *
 *		This initializes the limit node state structures and
 *		the node's subplan.
 * ----------------------------------------------------------------
 */
limit_ps *
ExecInitLimit(limit_pl *node, exec_state_n *estate, int eflags)
{
	limit_ps *limitstate;
	plan_n *outerPlan;

	/* check for unsupported flags */
	ASSERT(!(eflags & EXEC_FLAG_MARK));

	/*
	 * create state structure
	 */
	limitstate = MK_N(LimitState,limit_ps);
	limitstate->ps.plan = (plan_n *) node;
	limitstate->ps.state = estate;
	limitstate->lstate = LIMIT_INITIAL;

	/*
	 * Miscellaneous initialization
	 *
	 * limit_pl nodes never call exec_qual or exec_projection, but they need an
	 * exprcontext anyway to evaluate the limit/offset parameters in.
	 */
	ExecAssignExprContext(estate, &limitstate->ps);

	/*
	 * initialize child expressions
	 */
	limitstate->limitOffset = exec_init_expr(
		(expr_n*) node->limitOffset,
		(plan_state_n*) limitstate);

	limitstate->limitCount = exec_init_expr(
		(expr_n*) node->limitCount,
		(plan_state_n*) limitstate);

	/*
	 * Tuple table initialization (XXX not actually used...)
	 */
	exec_init_result_tupslot(estate, &limitstate->ps);

	/*
	 * then initialize outer plan
	 */
	outerPlan = OUTER_PLAN(node);
	OUTER_PLAN_STATE(limitstate) = exec_init_node(outerPlan, estate, eflags);

	/*
	 * limit nodes do no projections, so initialize projection info for this
	 * node appropriately
	 */
	ExecAssignResultTypeFromTL(&limitstate->ps);
	limitstate->ps.ps_ProjInfo = NULL;

	return limitstate;
}

/* ----------------------------------------------------------------
 *		ExecInitWorkTableScan
 * ----------------------------------------------------------------
 */
WorkTableScanState *
ExecInitWorkTableScan(WorkTableScan *node, EState *estate, int eflags)
{
	WorkTableScanState *scanstate;

	/* check for unsupported flags */
	Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));

	/*
	 * WorkTableScan should not have any children.
	 */
	Assert(outerPlan(node) == NULL);
	Assert(innerPlan(node) == NULL);

	/*
	 * create new WorkTableScanState for node
	 */
	scanstate = makeNode(WorkTableScanState);
	scanstate->ss.ps.plan = (Plan *) node;
	scanstate->ss.ps.state = estate;
	scanstate->ss.ps.ExecProcNode = ExecWorkTableScan;
	scanstate->rustate = NULL;	/* we'll set this later */

	/*
	 * Miscellaneous initialization
	 *
	 * create expression context for node
	 */
	ExecAssignExprContext(estate, &scanstate->ss.ps);

	/*
	 * tuple table initialization
	 */
	ExecInitResultTypeTL(&scanstate->ss.ps);

	/* signal that return type is not yet known */
	scanstate->ss.ps.resultopsset = true;
	scanstate->ss.ps.resultopsfixed = false;

	ExecInitScanTupleSlot(estate, &scanstate->ss, NULL, &TTSOpsMinimalTuple);

	/*
	 * initialize child expressions
	 */
	scanstate->ss.ps.qual =
		ExecInitQual(node->scan.plan.qual, (PlanState *) scanstate);

	/*
	 * Do not yet initialize projection info, see ExecWorkTableScan() for
	 * details.
	 */

	return scanstate;
}

/* ----------------------------------------------------------------
 *		ExecInitHash
 *
 *		Init routine for Hash node
 * ----------------------------------------------------------------
 */
HashState *
ExecInitHash(Hash *node, EState *estate)
{
	HashState  *hashstate;

	SO_printf("ExecInitHash: initializing hash node\n");

	/*
	 * create state structure
	 */
	hashstate = makeNode(HashState);
	hashstate->ps.plan = (Plan *) node;
	hashstate->ps.state = estate;
	hashstate->hashtable = NULL;
	hashstate->hashkeys = NIL;	/* will be set by parent HashJoin */

	/*
	 * Miscellaneous initialization
	 *
	 * create expression context for node
	 */
	ExecAssignExprContext(estate, &hashstate->ps);

#define HASH_NSLOTS 1

	/*
	 * initialize our result slot
	 */
	ExecInitResultTupleSlot(estate, &hashstate->ps);

	/*
	 * initialize child expressions
	 */
	hashstate->ps.targetlist = (List *)
		ExecInitExpr((Expr *) node->plan.targetlist,
					 (PlanState *) hashstate);
	hashstate->ps.qual = (List *)
		ExecInitExpr((Expr *) node->plan.qual,
					 (PlanState *) hashstate);

	/*
	 * initialize child nodes
	 */
	outerPlanState(hashstate) = ExecInitNode(outerPlan(node), estate);

	/*
	 * initialize tuple type. no need to initialize projection info
	 * because this node doesn't do projections
	 */
	ExecAssignResultTypeFromOuterPlan(&hashstate->ps);
	hashstate->ps.ps_ProjInfo = NULL;

	return hashstate;
}

/* ----------------------------------------------------------------
 *		ExecInitLimit
 *
 *		This initializes the limit node state structures and
 *		the node's subplan.
 * ----------------------------------------------------------------
 */
LimitState *
ExecInitLimit(Limit *node, EState *estate)
{
	LimitState *limitstate;
	Plan	   *outerPlan;

	/*
	 * create state structure
	 */
	limitstate = makeNode(LimitState);
	limitstate->ps.plan = (Plan *) node;
	limitstate->ps.state = estate;

	limitstate->lstate = LIMIT_INITIAL;

	/*
	 * Miscellaneous initialization
	 *
	 * Limit nodes never call ExecQual or ExecProject, but they need an
	 * exprcontext anyway to evaluate the limit/offset parameters in.
	 */
	ExecAssignExprContext(estate, &limitstate->ps);

	/*
	 * initialize child expressions
	 */
	limitstate->limitOffset = ExecInitExpr((Expr *) node->limitOffset,
										   (PlanState *) limitstate);
	limitstate->limitCount = ExecInitExpr((Expr *) node->limitCount,
										  (PlanState *) limitstate);

#define LIMIT_NSLOTS 1

	/*
	 * Tuple table initialization
	 */
	ExecInitResultTupleSlot(estate, &limitstate->ps);

	/*
	 * then initialize outer plan
	 */
	outerPlan = outerPlan(node);
	outerPlanState(limitstate) = ExecInitNode(outerPlan, estate);

	/*
	 * limit nodes do no projections, so initialize projection info for
	 * this node appropriately
	 */
	ExecAssignResultTypeFromOuterPlan(&limitstate->ps);
	limitstate->ps.ps_ProjInfo = NULL;

	return limitstate;
}

/* ----------------------------------------------------------------
 *		ExecInitHash
 *
 *		Init routine for hash_pl node
 * ----------------------------------------------------------------
 */
hash_ps *
ExecInitHash(hash_pl *node, exec_state_n *estate, int eflags)
{
	hash_ps* hashstate;

	/* check for unsupported flags */
	ASSERT(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));

	/*
	 * create state structure
	 */
	hashstate = MK_N(HashState,hash_ps);
	hashstate->ps.plan = (plan_n *) node;
	hashstate->ps.state = estate;
	hashstate->hashtable = NULL;
	hashstate->hashkeys = NIL;	/* will be set by parent hash_join_jo */

	/*
	 * Miscellaneous initialization
	 * create expression context for node
	 */
	ExecAssignExprContext(estate, &hashstate->ps);

	/*
	 * initialize our result slot
	 */
	exec_init_result_tupslot(estate, &hashstate->ps);

	/*
	 * initialize child expressions
	 */
	hashstate->ps.targetlist = (struct list*) exec_init_expr(
		(expr_n*) node->plan.targetlist,
		(plan_state_n*) hashstate);

	hashstate->ps.qual = (struct list*) exec_init_expr(
		(expr_n*) node->plan.qual,
		(plan_state_n *) hashstate);

	/*
	 * initialize child nodes
	 */
	OUTER_PLAN_STATE(hashstate) = exec_init_node(OUTER_PLAN(node), estate, eflags);

	/*
	 * initialize tuple type. no need to initialize projection info because
	 * this node doesn't do projections
	 */
	ExecAssignResultTypeFromTL(&hashstate->ps);
	hashstate->ps.ps_ProjInfo = NULL;

	return hashstate;
}

/* ----------------------------------------------------------------
 *		ExecInitResult
 *
 *		Creates the run-time state information for the result node
 *		produced by the planner and initializes outer relations
 *		(child nodes).
 * ----------------------------------------------------------------
 */
ResultState *
ExecInitResult(Result *node, EState *estate, int eflags)
{
	ResultState *resstate;

	/* check for unsupported flags */
	Assert(!(eflags & (EXEC_FLAG_MARK | EXEC_FLAG_BACKWARD)) ||
		   outerPlan(node) != NULL);

	/*
	 * create state structure
	 */
	resstate = makeNode(ResultState);
	resstate->ps.plan = (Plan *) node;
	resstate->ps.state = estate;
	resstate->ps.ExecProcNode = ExecResult;

	resstate->rs_done = false;
	resstate->rs_checkqual = (node->resconstantqual == NULL) ? false : true;

	/*
	 * Miscellaneous initialization
	 *
	 * create expression context for node
	 */
	ExecAssignExprContext(estate, &resstate->ps);

	/*
	 * initialize child nodes
	 */
	outerPlanState(resstate) = ExecInitNode(outerPlan(node), estate, eflags);

	/*
	 * we don't use inner plan
	 */
	Assert(innerPlan(node) == NULL);

	/*
	 * Initialize result slot, type and projection.
	 */
	ExecInitResultTupleSlotTL(&resstate->ps);
	ExecAssignProjectionInfo(&resstate->ps, NULL);

	/*
	 * initialize child expressions
	 */
	resstate->ps.qual =
		ExecInitQual(node->plan.qual, (PlanState *) resstate);
	resstate->resconstantqual =
		ExecInitQual((List *) node->resconstantqual, (PlanState *) resstate);

	return resstate;
}