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) 1996-2016, 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  */
40 typedef 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 
47 extern Tuplestorestate *tuplestore_begin_heap(bool randomAccess,
48 					  bool interXact,
49 					  int maxKBytes);
50 
51 extern void tuplestore_set_eflags(Tuplestorestate *state, int eflags);
52 
53 extern void tuplestore_puttupleslot(Tuplestorestate *state,
54 						TupleTableSlot *slot);
55 extern void tuplestore_puttuple(Tuplestorestate *state, HeapTuple tuple);
56 extern 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 
62 extern int	tuplestore_alloc_read_pointer(Tuplestorestate *state, int eflags);
63 
64 extern void tuplestore_select_read_pointer(Tuplestorestate *state, int ptr);
65 
66 extern void tuplestore_copy_read_pointer(Tuplestorestate *state,
67 							 int srcptr, int destptr);
68 
69 extern void tuplestore_trim(Tuplestorestate *state);
70 
71 extern bool tuplestore_in_memory(Tuplestorestate *state);
72 
73 extern bool tuplestore_gettupleslot(Tuplestorestate *state, bool forward,
74 						bool copy, TupleTableSlot *slot);
75 
76 extern bool tuplestore_advance(Tuplestorestate *state, bool forward);
77 
78 extern bool tuplestore_skiptuples(Tuplestorestate *state,
79 					  int64 ntuples, bool forward);
80 
81 extern bool tuplestore_ateof(Tuplestorestate *state);
82 
83 extern void tuplestore_rescan(Tuplestorestate *state);
84 
85 extern void tuplestore_clear(Tuplestorestate *state);
86 
87 extern void tuplestore_end(Tuplestorestate *state);
88 
89 #endif   /* TUPLESTORE_H */
90