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nodeSubqueryscan.c
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1 /*-------------------------------------------------------------------------
2  *
3  * nodeSubqueryscan.c
4  * Support routines for scanning subqueries (subselects in rangetable).
5  *
6  * This is just enough different from sublinks (nodeSubplan.c) to mean that
7  * we need two sets of code. Ought to look at trying to unify the cases.
8  *
9  *
10  * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
11  * Portions Copyright (c) 1994, Regents of the University of California
12  *
13  *
14  * IDENTIFICATION
15  * src/backend/executor/nodeSubqueryscan.c
16  *
17  *-------------------------------------------------------------------------
18  */
19 /*
20  * INTERFACE ROUTINES
21  * ExecSubqueryScan scans a subquery.
22  * ExecSubqueryNext retrieve next tuple in sequential order.
23  * ExecInitSubqueryScan creates and initializes a subqueryscan node.
24  * ExecEndSubqueryScan releases any storage allocated.
25  * ExecReScanSubqueryScan rescans the relation
26  *
27  */
28 #include "postgres.h"
29 
30 #include "executor/execdebug.h"
32 
34 
35 /* ----------------------------------------------------------------
36  * Scan Support
37  * ----------------------------------------------------------------
38  */
39 /* ----------------------------------------------------------------
40  * SubqueryNext
41  *
42  * This is a workhorse for ExecSubqueryScan
43  * ----------------------------------------------------------------
44  */
45 static TupleTableSlot *
47 {
48  TupleTableSlot *slot;
49 
50  /*
51  * Get the next tuple from the sub-query.
52  */
53  slot = ExecProcNode(node->subplan);
54 
55  /*
56  * We just return the subplan's result slot, rather than expending extra
57  * cycles for ExecCopySlot(). (Our own ScanTupleSlot is used only for
58  * EvalPlanQual rechecks.)
59  */
60  return slot;
61 }
62 
63 /*
64  * SubqueryRecheck -- access method routine to recheck a tuple in EvalPlanQual
65  */
66 static bool
68 {
69  /* nothing to check */
70  return true;
71 }
72 
73 /* ----------------------------------------------------------------
74  * ExecSubqueryScan(node)
75  *
76  * Scans the subquery sequentially and returns the next qualifying
77  * tuple.
78  * We call the ExecScan() routine and pass it the appropriate
79  * access method functions.
80  * ----------------------------------------------------------------
81  */
82 static TupleTableSlot *
84 {
86 
87  return ExecScan(&node->ss,
90 }
91 
92 /* ----------------------------------------------------------------
93  * ExecInitSubqueryScan
94  * ----------------------------------------------------------------
95  */
97 ExecInitSubqueryScan(SubqueryScan *node, EState *estate, int eflags)
98 {
99  SubqueryScanState *subquerystate;
100 
101  /* check for unsupported flags */
102  Assert(!(eflags & EXEC_FLAG_MARK));
103 
104  /* SubqueryScan should not have any "normal" children */
105  Assert(outerPlan(node) == NULL);
106  Assert(innerPlan(node) == NULL);
107 
108  /*
109  * create state structure
110  */
111  subquerystate = makeNode(SubqueryScanState);
112  subquerystate->ss.ps.plan = (Plan *) node;
113  subquerystate->ss.ps.state = estate;
114  subquerystate->ss.ps.ExecProcNode = ExecSubqueryScan;
115 
116  /*
117  * Miscellaneous initialization
118  *
119  * create expression context for node
120  */
121  ExecAssignExprContext(estate, &subquerystate->ss.ps);
122 
123  /*
124  * initialize subquery
125  */
126  subquerystate->subplan = ExecInitNode(node->subplan, estate, eflags);
127 
128  /*
129  * Initialize scan slot and type (needed by ExecInitResultTupleSlotTL)
130  */
131  ExecInitScanTupleSlot(estate, &subquerystate->ss,
132  ExecGetResultType(subquerystate->subplan));
133 
134  /*
135  * Initialize result slot, type and projection.
136  */
137  ExecInitResultTupleSlotTL(estate, &subquerystate->ss.ps);
138  ExecAssignScanProjectionInfo(&subquerystate->ss);
139 
140  /*
141  * initialize child expressions
142  */
143  subquerystate->ss.ps.qual =
144  ExecInitQual(node->scan.plan.qual, (PlanState *) subquerystate);
145 
146  return subquerystate;
147 }
148 
149 /* ----------------------------------------------------------------
150  * ExecEndSubqueryScan
151  *
152  * frees any storage allocated through C routines.
153  * ----------------------------------------------------------------
154  */
155 void
157 {
158  /*
159  * Free the exprcontext
160  */
161  ExecFreeExprContext(&node->ss.ps);
162 
163  /*
164  * clean out the upper tuple table
165  */
168 
169  /*
170  * close down subquery
171  */
172  ExecEndNode(node->subplan);
173 }
174 
175 /* ----------------------------------------------------------------
176  * ExecReScanSubqueryScan
177  *
178  * Rescans the relation.
179  * ----------------------------------------------------------------
180  */
181 void
183 {
184  ExecScanReScan(&node->ss);
185 
186  /*
187  * ExecReScan doesn't know about my subplan, so I have to do
188  * changed-parameter signaling myself. This is just as well, because the
189  * subplan has its own memory context in which its chgParam state lives.
190  */
191  if (node->ss.ps.chgParam != NULL)
193 
194  /*
195  * if chgParam of subnode is not null then plan will be re-scanned by
196  * first ExecProcNode.
197  */
198  if (node->subplan->chgParam == NULL)
199  ExecReScan(node->subplan);
200 }
List * qual
Definition: plannodes.h:147
Plan plan
Definition: plannodes.h:342
static TupleTableSlot * ExecSubqueryScan(PlanState *pstate)
#define castNode(_type_, nodeptr)
Definition: nodes.h:586
void ExecEndNode(PlanState *node)
Definition: execProcnode.c:538
TupleTableSlot * ExecScan(ScanState *node, ExecScanAccessMtd accessMtd, ExecScanRecheckMtd recheckMtd)
Definition: execScan.c:121
void ExecReScan(PlanState *node)
Definition: execAmi.c:76
static TupleTableSlot * SubqueryNext(SubqueryScanState *node)
TupleTableSlot * ExecClearTuple(TupleTableSlot *slot)
Definition: execTuples.c:475
TupleTableSlot * ss_ScanTupleSlot
Definition: execnodes.h:1195
EState * state
Definition: execnodes.h:914
void ExecFreeExprContext(PlanState *planstate)
Definition: execUtils.c:566
ExprState * ExecInitQual(List *qual, PlanState *parent)
Definition: execExpr.c:205
void ExecEndSubqueryScan(SubqueryScanState *node)
PlanState ps
Definition: execnodes.h:1192
TupleTableSlot * ps_ResultTupleSlot
Definition: execnodes.h:946
void ExecAssignScanProjectionInfo(ScanState *node)
Definition: execScan.c:235
#define innerPlan(node)
Definition: plannodes.h:175
SubqueryScanState * ExecInitSubqueryScan(SubqueryScan *node, EState *estate, int eflags)
PlanState * subplan
Definition: execnodes.h:1494
Bitmapset * chgParam
Definition: execnodes.h:941
#define outerPlan(node)
Definition: plannodes.h:176
bool(* ExecScanRecheckMtd)(ScanState *node, TupleTableSlot *slot)
Definition: executor.h:422
ExecProcNodeMtd ExecProcNode
Definition: execnodes.h:918
static TupleTableSlot * ExecProcNode(PlanState *node)
Definition: executor.h:233
void ExecReScanSubqueryScan(SubqueryScanState *node)
void ExecInitResultTupleSlotTL(EState *estate, PlanState *planstate)
Definition: execTuples.c:890
Plan * plan
Definition: execnodes.h:912
void UpdateChangedParamSet(PlanState *node, Bitmapset *newchg)
Definition: execUtils.c:711
#define makeNode(_type_)
Definition: nodes.h:565
static bool SubqueryRecheck(SubqueryScanState *node, TupleTableSlot *slot)
#define Assert(condition)
Definition: c.h:699
#define EXEC_FLAG_MARK
Definition: executor.h:61
void ExecAssignExprContext(EState *estate, PlanState *planstate)
Definition: execUtils.c:428
TupleDesc ExecGetResultType(PlanState *planstate)
Definition: execUtils.c:438
ExprState * qual
Definition: execnodes.h:930
void ExecScanReScan(ScanState *node)
Definition: execScan.c:262
void ExecInitScanTupleSlot(EState *estate, ScanState *scanstate, TupleDesc tupledesc)
Definition: execTuples.c:915
TupleTableSlot *(* ExecScanAccessMtd)(ScanState *node)
Definition: executor.h:421
PlanState * ExecInitNode(Plan *node, EState *estate, int eflags)
Definition: execProcnode.c:139
Plan * subplan
Definition: plannodes.h:512