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toast_helper.h
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1 /*-------------------------------------------------------------------------
2  *
3  * toast_helper.h
4  * Helper functions for table AMs implementing compressed or
5  * out-of-line storage of varlena attributes.
6  *
7  * Copyright (c) 2000-2021, PostgreSQL Global Development Group
8  *
9  * src/include/access/toast_helper.h
10  *
11  *-------------------------------------------------------------------------
12  */
13 
14 #ifndef TOAST_HELPER_H
15 #define TOAST_HELPER_H
16 
17 #include "utils/rel.h"
18 
19 /*
20  * Information about one column of a tuple being toasted.
21  *
22  * NOTE: toast_action[i] can have these values:
23  * ' ' default handling
24  * TYPSTORAGE_PLAIN already processed --- don't touch it
25  * TYPSTORAGE_EXTENDED incompressible, but OK to move off
26  *
27  * NOTE: toast_attr[i].tai_size is only made valid for varlena attributes with
28  * toast_action[i] different from TYPSTORAGE_PLAIN.
29  */
30 typedef struct
31 {
37 
38 /*
39  * Information about one tuple being toasted.
40  */
41 typedef struct
42 {
43  /*
44  * Before calling toast_tuple_init, the caller must initialize the
45  * following fields. Each array must have a length equal to
46  * ttc_rel->rd_att->natts. The tts_oldvalues and tts_oldisnull fields
47  * should be NULL in the case of an insert.
48  */
49  Relation ttc_rel; /* the relation that contains the tuple */
50  Datum *ttc_values; /* values from the tuple columns */
51  bool *ttc_isnull; /* null flags for the tuple columns */
52  Datum *ttc_oldvalues; /* values from previous tuple */
53  bool *ttc_oldisnull; /* null flags from previous tuple */
54 
55  /*
56  * Before calling toast_tuple_init, the caller should set tts_attr to
57  * point to an array of ToastAttrInfo structures of a length equal to
58  * tts_rel->rd_att->natts. The contents of the array need not be
59  * initialized. ttc_flags also does not need to be initialized.
60  */
64 
65 /*
66  * Flags indicating the overall state of a TOAST operation.
67  *
68  * TOAST_NEEDS_DELETE_OLD indicates that one or more old TOAST datums need
69  * to be deleted.
70  *
71  * TOAST_NEEDS_FREE indicates that one or more TOAST values need to be freed.
72  *
73  * TOAST_HAS_NULLS indicates that nulls were found in the tuple being toasted.
74  *
75  * TOAST_NEEDS_CHANGE indicates that a new tuple needs to built; in other
76  * words, the toaster did something.
77  */
78 #define TOAST_NEEDS_DELETE_OLD 0x0001
79 #define TOAST_NEEDS_FREE 0x0002
80 #define TOAST_HAS_NULLS 0x0004
81 #define TOAST_NEEDS_CHANGE 0x0008
82 
83 /*
84  * Flags indicating the status of a TOAST operation with respect to a
85  * particular column.
86  *
87  * TOASTCOL_NEEDS_DELETE_OLD indicates that the old TOAST datums for this
88  * column need to be deleted.
89  *
90  * TOASTCOL_NEEDS_FREE indicates that the value for this column needs to
91  * be freed.
92  *
93  * TOASTCOL_IGNORE indicates that the toaster should not further process
94  * this column.
95  *
96  * TOASTCOL_INCOMPRESSIBLE indicates that this column has been found to
97  * be incompressible, but could be moved out-of-line.
98  */
99 #define TOASTCOL_NEEDS_DELETE_OLD TOAST_NEEDS_DELETE_OLD
100 #define TOASTCOL_NEEDS_FREE TOAST_NEEDS_FREE
101 #define TOASTCOL_IGNORE 0x0010
102 #define TOASTCOL_INCOMPRESSIBLE 0x0020
103 
104 extern void toast_tuple_init(ToastTupleContext *ttc);
106  bool for_compression,
107  bool check_main);
108 extern void toast_tuple_try_compression(ToastTupleContext *ttc, int attribute);
109 extern void toast_tuple_externalize(ToastTupleContext *ttc, int attribute,
110  int options);
111 extern void toast_tuple_cleanup(ToastTupleContext *ttc);
112 
113 extern void toast_delete_external(Relation rel, Datum *values, bool *isnull,
114  bool is_speculative);
115 
116 #endif
uint8 tai_colflags
Definition: toast_helper.h:34
void toast_tuple_try_compression(ToastTupleContext *ttc, int attribute)
Definition: toast_helper.c:227
unsigned char uint8
Definition: c.h:439
signed int int32
Definition: c.h:429
int toast_tuple_find_biggest_attribute(ToastTupleContext *ttc, bool for_compression, bool check_main)
Definition: toast_helper.c:181
char tai_compression
Definition: toast_helper.h:35
void toast_delete_external(Relation rel, Datum *values, bool *isnull, bool is_speculative)
Definition: toast_helper.c:318
void toast_tuple_externalize(ToastTupleContext *ttc, int attribute, int options)
Definition: toast_helper.c:256
void toast_tuple_cleanup(ToastTupleContext *ttc)
Definition: toast_helper.c:275
uintptr_t Datum
Definition: postgres.h:411
Datum * ttc_oldvalues
Definition: toast_helper.h:52
static Datum values[MAXATTR]
Definition: bootstrap.c:166
void toast_tuple_init(ToastTupleContext *ttc)
Definition: toast_helper.c:41
struct varlena * tai_oldexternal
Definition: toast_helper.h:32
Definition: c.h:621
ToastAttrInfo * ttc_attr
Definition: toast_helper.h:62