1/*-------------------------------------------------------------------------
2 *
3 * tuplestore.h
4 * Generalized routines for temporary tuple storage.
5 *
6 * This module handles temporary storage of tuples for purposes such
7 * as Materialize nodes, hashjoin batch files, etc. It is essentially
8 * a dumbed-down version of tuplesort.c; it does no sorting of tuples
9 * but can only store and regurgitate a sequence of tuples. However,
10 * because no sort is required, it is allowed to start reading the sequence
11 * before it has all been written. This is particularly useful for cursors,
12 * because it allows random access within the already-scanned portion of
13 * a query without having to process the underlying scan to completion.
14 * Also, it is possible to support multiple independent read pointers.
15 *
16 * A temporary file is used to handle the data if it exceeds the
17 * space limit specified by the caller.
18 *
19 * Beginning in Postgres 8.2, what is stored is just MinimalTuples;
20 * callers cannot expect valid system columns in regurgitated tuples.
21 * Also, we have changed the API to return tuples in TupleTableSlots,
22 * so that there is a check to prevent attempted access to system columns.
23 *
24 * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
25 * Portions Copyright (c) 1994, Regents of the University of California
26 *
27 * src/include/utils/tuplestore.h
28 *
29 *-------------------------------------------------------------------------
30 */
31#ifndef TUPLESTORE_H
32#define TUPLESTORE_H
33
34#include "executor/tuptable.h"
35
36
37/* Tuplestorestate is an opaque type whose details are not known outside
38 * tuplestore.c.
39 */
40typedef struct Tuplestorestate Tuplestorestate;
41
42/*
43 * Currently we only need to store MinimalTuples, but it would be easy
44 * to support the same behavior for IndexTuples and/or bare Datums.
45 */
46
47extern Tuplestorestate *tuplestore_begin_heap(bool randomAccess,
48 bool interXact,
49 int maxKBytes);
50
51extern void tuplestore_set_eflags(Tuplestorestate *state, int eflags);
52
53extern void tuplestore_puttupleslot(Tuplestorestate *state,
54 TupleTableSlot *slot);
55extern void tuplestore_puttuple(Tuplestorestate *state, HeapTuple tuple);
56extern void tuplestore_putvalues(Tuplestorestate *state, TupleDesc tdesc,
57 Datum *values, bool *isnull);
58
59/* tuplestore_donestoring() used to be required, but is no longer used */
60#define tuplestore_donestoring(state) ((void) 0)
61
62extern int tuplestore_alloc_read_pointer(Tuplestorestate *state, int eflags);
63
64extern void tuplestore_select_read_pointer(Tuplestorestate *state, int ptr);
65
66extern void tuplestore_copy_read_pointer(Tuplestorestate *state,
67 int srcptr, int destptr);
68
69extern void tuplestore_trim(Tuplestorestate *state);
70
71extern bool tuplestore_in_memory(Tuplestorestate *state);
72
73extern bool tuplestore_gettupleslot(Tuplestorestate *state, bool forward,
74 bool copy, TupleTableSlot *slot);
75
76extern bool tuplestore_advance(Tuplestorestate *state, bool forward);
77
78extern bool tuplestore_skiptuples(Tuplestorestate *state,
79 int64 ntuples, bool forward);
80
81extern int64 tuplestore_tuple_count(Tuplestorestate *state);
82
83extern bool tuplestore_ateof(Tuplestorestate *state);
84
85extern void tuplestore_rescan(Tuplestorestate *state);
86
87extern void tuplestore_clear(Tuplestorestate *state);
88
89extern void tuplestore_end(Tuplestorestate *state);
90
91#endif /* TUPLESTORE_H */
92