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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) 1996-2017, 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 child expressions
125  */
126  subquerystate->ss.ps.qual =
127  ExecInitQual(node->scan.plan.qual, (PlanState *) subquerystate);
128 
129  /*
130  * tuple table initialization
131  */
132  ExecInitResultTupleSlot(estate, &subquerystate->ss.ps);
133  ExecInitScanTupleSlot(estate, &subquerystate->ss);
134 
135  /*
136  * initialize subquery
137  */
138  subquerystate->subplan = ExecInitNode(node->subplan, estate, eflags);
139 
140  /*
141  * Initialize scan tuple type (needed by ExecAssignScanProjectionInfo)
142  */
143  ExecAssignScanType(&subquerystate->ss,
144  ExecGetResultType(subquerystate->subplan));
145 
146  /*
147  * Initialize result tuple type and projection info.
148  */
149  ExecAssignResultTypeFromTL(&subquerystate->ss.ps);
150  ExecAssignScanProjectionInfo(&subquerystate->ss);
151 
152  return subquerystate;
153 }
154 
155 /* ----------------------------------------------------------------
156  * ExecEndSubqueryScan
157  *
158  * frees any storage allocated through C routines.
159  * ----------------------------------------------------------------
160  */
161 void
163 {
164  /*
165  * Free the exprcontext
166  */
167  ExecFreeExprContext(&node->ss.ps);
168 
169  /*
170  * clean out the upper tuple table
171  */
174 
175  /*
176  * close down subquery
177  */
178  ExecEndNode(node->subplan);
179 }
180 
181 /* ----------------------------------------------------------------
182  * ExecReScanSubqueryScan
183  *
184  * Rescans the relation.
185  * ----------------------------------------------------------------
186  */
187 void
189 {
190  ExecScanReScan(&node->ss);
191 
192  /*
193  * ExecReScan doesn't know about my subplan, so I have to do
194  * changed-parameter signaling myself. This is just as well, because the
195  * subplan has its own memory context in which its chgParam state lives.
196  */
197  if (node->ss.ps.chgParam != NULL)
199 
200  /*
201  * if chgParam of subnode is not null then plan will be re-scanned by
202  * first ExecProcNode.
203  */
204  if (node->subplan->chgParam == NULL)
205  ExecReScan(node->subplan);
206 }
List * qual
Definition: plannodes.h:145
Plan plan
Definition: plannodes.h:328
static TupleTableSlot * ExecSubqueryScan(PlanState *pstate)
void ExecInitScanTupleSlot(EState *estate, ScanState *scanstate)
Definition: execTuples.c:842
#define castNode(_type_, nodeptr)
Definition: nodes.h:579
void ExecEndNode(PlanState *node)
Definition: execProcnode.c:523
TupleTableSlot * ExecScan(ScanState *node, ExecScanAccessMtd accessMtd, ExecScanRecheckMtd recheckMtd)
Definition: execScan.c:123
void ExecReScan(PlanState *node)
Definition: execAmi.c:76
static TupleTableSlot * SubqueryNext(SubqueryScanState *node)
TupleTableSlot * ExecClearTuple(TupleTableSlot *slot)
Definition: execTuples.c:439
TupleTableSlot * ss_ScanTupleSlot
Definition: execnodes.h:1104
EState * state
Definition: execnodes.h:849
void ExecFreeExprContext(PlanState *planstate)
Definition: execUtils.c:521
ExprState * ExecInitQual(List *qual, PlanState *parent)
Definition: execExpr.c:160
void ExecAssignResultTypeFromTL(PlanState *planstate)
Definition: execUtils.c:445
void ExecEndSubqueryScan(SubqueryScanState *node)
TupleTableSlot *(* ExecScanAccessMtd)(ScanState *node)
Definition: executor.h:410
PlanState ps
Definition: execnodes.h:1101
bool(* ExecScanRecheckMtd)(ScanState *node, TupleTableSlot *slot)
Definition: executor.h:411
TupleTableSlot * ps_ResultTupleSlot
Definition: execnodes.h:880
void ExecAssignScanProjectionInfo(ScanState *node)
Definition: execScan.c:237
void ExecInitResultTupleSlot(EState *estate, PlanState *planstate)
Definition: execTuples.c:832
#define innerPlan(node)
Definition: plannodes.h:173
SubqueryScanState * ExecInitSubqueryScan(SubqueryScan *node, EState *estate, int eflags)
PlanState * subplan
Definition: execnodes.h:1397
Bitmapset * chgParam
Definition: execnodes.h:875
#define outerPlan(node)
Definition: plannodes.h:174
ExecProcNodeMtd ExecProcNode
Definition: execnodes.h:853
static TupleTableSlot * ExecProcNode(PlanState *node)
Definition: executor.h:246
void ExecReScanSubqueryScan(SubqueryScanState *node)
Plan * plan
Definition: execnodes.h:847
void UpdateChangedParamSet(PlanState *node, Bitmapset *newchg)
Definition: execUtils.c:676
#define makeNode(_type_)
Definition: nodes.h:558
static bool SubqueryRecheck(SubqueryScanState *node, TupleTableSlot *slot)
#define Assert(condition)
Definition: c.h:681
#define EXEC_FLAG_MARK
Definition: executor.h:61
void ExecAssignExprContext(EState *estate, PlanState *planstate)
Definition: execUtils.c:423
TupleDesc ExecGetResultType(PlanState *planstate)
Definition: execUtils.c:474
ExprState * qual
Definition: execnodes.h:865
void ExecScanReScan(ScanState *node)
Definition: execScan.c:329
void ExecAssignScanType(ScanState *scanstate, TupleDesc tupDesc)
Definition: execUtils.c:545
PlanState * ExecInitNode(Plan *node, EState *estate, int eflags)
Definition: execProcnode.c:139
Plan * subplan
Definition: plannodes.h:498