Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * nodeNamedtuplestorescan.c
4 : * routines to handle NamedTuplestoreScan nodes.
5 : *
6 : * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
7 : * Portions Copyright (c) 1994, Regents of the University of California
8 : *
9 : *
10 : * IDENTIFICATION
11 : * src/backend/executor/nodeNamedtuplestorescan.c
12 : *
13 : *-------------------------------------------------------------------------
14 : */
15 :
16 : #include "postgres.h"
17 :
18 : #include "executor/executor.h"
19 : #include "executor/nodeNamedtuplestorescan.h"
20 : #include "utils/queryenvironment.h"
21 :
22 : static TupleTableSlot *NamedTuplestoreScanNext(NamedTuplestoreScanState *node);
23 :
24 : /* ----------------------------------------------------------------
25 : * NamedTuplestoreScanNext
26 : *
27 : * This is a workhorse for ExecNamedTuplestoreScan
28 : * ----------------------------------------------------------------
29 : */
30 : static TupleTableSlot *
31 33345 : NamedTuplestoreScanNext(NamedTuplestoreScanState *node)
32 : {
33 : TupleTableSlot *slot;
34 :
35 : /* We intentionally do not support backward scan. */
36 : Assert(ScanDirectionIsForward(node->ss.ps.state->es_direction));
37 :
38 : /*
39 : * Get the next tuple from tuplestore. Return NULL if no more tuples.
40 : */
41 33345 : slot = node->ss.ss_ScanTupleSlot;
42 33345 : tuplestore_select_read_pointer(node->relation, node->readptr);
43 33345 : (void) tuplestore_gettupleslot(node->relation, true, false, slot);
44 33345 : return slot;
45 : }
46 :
47 : /*
48 : * NamedTuplestoreScanRecheck -- access method routine to recheck a tuple in
49 : * EvalPlanQual
50 : */
51 : static bool
52 0 : NamedTuplestoreScanRecheck(NamedTuplestoreScanState *node, TupleTableSlot *slot)
53 : {
54 : /* nothing to check */
55 0 : return true;
56 : }
57 :
58 : /* ----------------------------------------------------------------
59 : * ExecNamedTuplestoreScan(node)
60 : *
61 : * Scans the CTE sequentially and returns the next qualifying tuple.
62 : * We call the ExecScan() routine and pass it the appropriate
63 : * access method functions.
64 : * ----------------------------------------------------------------
65 : */
66 : static TupleTableSlot *
67 33345 : ExecNamedTuplestoreScan(PlanState *pstate)
68 : {
69 33345 : NamedTuplestoreScanState *node = castNode(NamedTuplestoreScanState, pstate);
70 :
71 33345 : return ExecScan(&node->ss,
72 : (ExecScanAccessMtd) NamedTuplestoreScanNext,
73 : (ExecScanRecheckMtd) NamedTuplestoreScanRecheck);
74 : }
75 :
76 :
77 : /* ----------------------------------------------------------------
78 : * ExecInitNamedTuplestoreScan
79 : * ----------------------------------------------------------------
80 : */
81 : NamedTuplestoreScanState *
82 345 : ExecInitNamedTuplestoreScan(NamedTuplestoreScan *node, EState *estate, int eflags)
83 : {
84 : NamedTuplestoreScanState *scanstate;
85 : EphemeralNamedRelation enr;
86 :
87 : /* check for unsupported flags */
88 : Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
89 :
90 : /*
91 : * NamedTuplestoreScan should not have any children.
92 : */
93 : Assert(outerPlan(node) == NULL);
94 : Assert(innerPlan(node) == NULL);
95 :
96 : /*
97 : * create new NamedTuplestoreScanState for node
98 : */
99 345 : scanstate = makeNode(NamedTuplestoreScanState);
100 345 : scanstate->ss.ps.plan = (Plan *) node;
101 345 : scanstate->ss.ps.state = estate;
102 345 : scanstate->ss.ps.ExecProcNode = ExecNamedTuplestoreScan;
103 :
104 345 : enr = get_ENR(estate->es_queryEnv, node->enrname);
105 345 : if (!enr)
106 0 : elog(ERROR, "executor could not find named tuplestore \"%s\"",
107 : node->enrname);
108 :
109 : Assert(enr->reldata);
110 345 : scanstate->relation = (Tuplestorestate *) enr->reldata;
111 345 : scanstate->tupdesc = ENRMetadataGetTupDesc(&(enr->md));
112 345 : scanstate->readptr =
113 345 : tuplestore_alloc_read_pointer(scanstate->relation, EXEC_FLAG_REWIND);
114 :
115 : /*
116 : * The new read pointer copies its position from read pointer 0, which
117 : * could be anywhere, so explicitly rewind it.
118 : */
119 345 : tuplestore_select_read_pointer(scanstate->relation, scanstate->readptr);
120 345 : tuplestore_rescan(scanstate->relation);
121 :
122 : /*
123 : * XXX: Should we add a function to free that read pointer when done?
124 : *
125 : * This was attempted, but it did not improve performance or memory usage
126 : * in any tested cases.
127 : */
128 :
129 : /*
130 : * Miscellaneous initialization
131 : *
132 : * create expression context for node
133 : */
134 345 : ExecAssignExprContext(estate, &scanstate->ss.ps);
135 :
136 : /*
137 : * The scan tuple type is specified for the tuplestore.
138 : */
139 345 : ExecInitScanTupleSlot(estate, &scanstate->ss, scanstate->tupdesc,
140 : &TTSOpsMinimalTuple);
141 :
142 : /*
143 : * Initialize result type and projection.
144 : */
145 345 : ExecInitResultTypeTL(&scanstate->ss.ps);
146 345 : ExecAssignScanProjectionInfo(&scanstate->ss);
147 :
148 : /*
149 : * initialize child expressions
150 : */
151 345 : scanstate->ss.ps.qual =
152 345 : ExecInitQual(node->scan.plan.qual, (PlanState *) scanstate);
153 :
154 345 : return scanstate;
155 : }
156 :
157 : /* ----------------------------------------------------------------
158 : * ExecReScanNamedTuplestoreScan
159 : *
160 : * Rescans the relation.
161 : * ----------------------------------------------------------------
162 : */
163 : void
164 0 : ExecReScanNamedTuplestoreScan(NamedTuplestoreScanState *node)
165 : {
166 0 : Tuplestorestate *tuplestorestate = node->relation;
167 :
168 0 : if (node->ss.ps.ps_ResultTupleSlot)
169 0 : ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
170 :
171 0 : ExecScanReScan(&node->ss);
172 :
173 : /*
174 : * Rewind my own pointer.
175 : */
176 0 : tuplestore_select_read_pointer(tuplestorestate, node->readptr);
177 0 : tuplestore_rescan(tuplestorestate);
178 0 : }
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