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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  */
84 {
85  return ExecScan(&node->ss,
88 }
89 
90 /* ----------------------------------------------------------------
91  * ExecInitSubqueryScan
92  * ----------------------------------------------------------------
93  */
95 ExecInitSubqueryScan(SubqueryScan *node, EState *estate, int eflags)
96 {
97  SubqueryScanState *subquerystate;
98 
99  /* check for unsupported flags */
100  Assert(!(eflags & EXEC_FLAG_MARK));
101 
102  /* SubqueryScan should not have any "normal" children */
103  Assert(outerPlan(node) == NULL);
104  Assert(innerPlan(node) == NULL);
105 
106  /*
107  * create state structure
108  */
109  subquerystate = makeNode(SubqueryScanState);
110  subquerystate->ss.ps.plan = (Plan *) node;
111  subquerystate->ss.ps.state = estate;
112 
113  /*
114  * Miscellaneous initialization
115  *
116  * create expression context for node
117  */
118  ExecAssignExprContext(estate, &subquerystate->ss.ps);
119 
120  /*
121  * initialize child expressions
122  */
123  subquerystate->ss.ps.qual =
124  ExecInitQual(node->scan.plan.qual, (PlanState *) subquerystate);
125 
126  /*
127  * tuple table initialization
128  */
129  ExecInitResultTupleSlot(estate, &subquerystate->ss.ps);
130  ExecInitScanTupleSlot(estate, &subquerystate->ss);
131 
132  /*
133  * initialize subquery
134  */
135  subquerystate->subplan = ExecInitNode(node->subplan, estate, eflags);
136 
137  /*
138  * Initialize scan tuple type (needed by ExecAssignScanProjectionInfo)
139  */
140  ExecAssignScanType(&subquerystate->ss,
141  ExecGetResultType(subquerystate->subplan));
142 
143  /*
144  * Initialize result tuple type and projection info.
145  */
146  ExecAssignResultTypeFromTL(&subquerystate->ss.ps);
147  ExecAssignScanProjectionInfo(&subquerystate->ss);
148 
149  return subquerystate;
150 }
151 
152 /* ----------------------------------------------------------------
153  * ExecEndSubqueryScan
154  *
155  * frees any storage allocated through C routines.
156  * ----------------------------------------------------------------
157  */
158 void
160 {
161  /*
162  * Free the exprcontext
163  */
164  ExecFreeExprContext(&node->ss.ps);
165 
166  /*
167  * clean out the upper tuple table
168  */
171 
172  /*
173  * close down subquery
174  */
175  ExecEndNode(node->subplan);
176 }
177 
178 /* ----------------------------------------------------------------
179  * ExecReScanSubqueryScan
180  *
181  * Rescans the relation.
182  * ----------------------------------------------------------------
183  */
184 void
186 {
187  ExecScanReScan(&node->ss);
188 
189  /*
190  * ExecReScan doesn't know about my subplan, so I have to do
191  * changed-parameter signaling myself. This is just as well, because the
192  * subplan has its own memory context in which its chgParam state lives.
193  */
194  if (node->ss.ps.chgParam != NULL)
196 
197  /*
198  * if chgParam of subnode is not null then plan will be re-scanned by
199  * first ExecProcNode.
200  */
201  if (node->subplan->chgParam == NULL)
202  ExecReScan(node->subplan);
203 }
List * qual
Definition: plannodes.h:145
TupleTableSlot * ExecProcNode(PlanState *node)
Definition: execProcnode.c:398
Plan plan
Definition: plannodes.h:328
void ExecInitScanTupleSlot(EState *estate, ScanState *scanstate)
Definition: execTuples.c:842
void ExecEndNode(PlanState *node)
Definition: execProcnode.c:654
TupleTableSlot * ExecScan(ScanState *node, ExecScanAccessMtd accessMtd, ExecScanRecheckMtd recheckMtd)
Definition: execScan.c:121
void ExecReScan(PlanState *node)
Definition: execAmi.c:75
static TupleTableSlot * SubqueryNext(SubqueryScanState *node)
TupleTableSlot * ExecClearTuple(TupleTableSlot *slot)
Definition: execTuples.c:439
TupleTableSlot * ss_ScanTupleSlot
Definition: execnodes.h:1078
EState * state
Definition: execnodes.h:834
void ExecFreeExprContext(PlanState *planstate)
Definition: execUtils.c:516
ExprState * ExecInitQual(List *qual, PlanState *parent)
Definition: execExpr.c:160
void ExecAssignResultTypeFromTL(PlanState *planstate)
Definition: execUtils.c:440
void ExecEndSubqueryScan(SubqueryScanState *node)
TupleTableSlot *(* ExecScanAccessMtd)(ScanState *node)
Definition: executor.h:389
PlanState ps
Definition: execnodes.h:1075
bool(* ExecScanRecheckMtd)(ScanState *node, TupleTableSlot *slot)
Definition: executor.h:390
TupleTableSlot * ps_ResultTupleSlot
Definition: execnodes.h:861
void ExecAssignScanProjectionInfo(ScanState *node)
Definition: execScan.c:235
void ExecInitResultTupleSlot(EState *estate, PlanState *planstate)
Definition: execTuples.c:832
#define innerPlan(node)
Definition: plannodes.h:173
TupleTableSlot * ExecSubqueryScan(SubqueryScanState *node)
SubqueryScanState * ExecInitSubqueryScan(SubqueryScan *node, EState *estate, int eflags)
PlanState * subplan
Definition: execnodes.h:1371
Bitmapset * chgParam
Definition: execnodes.h:856
#define outerPlan(node)
Definition: plannodes.h:174
void ExecReScanSubqueryScan(SubqueryScanState *node)
Plan * plan
Definition: execnodes.h:832
void UpdateChangedParamSet(PlanState *node, Bitmapset *newchg)
Definition: execUtils.c:671
#define makeNode(_type_)
Definition: nodes.h:557
#define NULL
Definition: c.h:229
static bool SubqueryRecheck(SubqueryScanState *node, TupleTableSlot *slot)
#define Assert(condition)
Definition: c.h:675
#define EXEC_FLAG_MARK
Definition: executor.h:61
void ExecAssignExprContext(EState *estate, PlanState *planstate)
Definition: execUtils.c:418
TupleDesc ExecGetResultType(PlanState *planstate)
Definition: execUtils.c:469
ExprState * qual
Definition: execnodes.h:846
void ExecScanReScan(ScanState *node)
Definition: execScan.c:327
void ExecAssignScanType(ScanState *scanstate, TupleDesc tupDesc)
Definition: execUtils.c:540
PlanState * ExecInitNode(Plan *node, EState *estate, int eflags)
Definition: execProcnode.c:140
Plan * subplan
Definition: plannodes.h:498