PostgreSQL Source Code: src/include/access/toast_helper.h Source File

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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) 2000-2025, 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{
32 struct varlena *tai_oldexternal;
33 int32 tai_size;
34 uint8 tai_colflags;
35 char tai_compression;
36} ToastAttrInfo;
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 ttc_oldvalues and ttc_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 ttc_attr to
57 * point to an array of ToastAttrInfo structures of a length equal to
58 * ttc_rel->rd_att->natts. The contents of the array need not be
59 * initialized. ttc_flags also does not need to be initialized.
60 */
61 uint8 ttc_flags;
62 ToastAttrInfo *ttc_attr;
63} ToastTupleContext;
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
104extern void toast_tuple_init(ToastTupleContext *ttc);
105extern int toast_tuple_find_biggest_attribute(ToastTupleContext *ttc,
106 bool for_compression,
107 bool check_main);
108extern void toast_tuple_try_compression(ToastTupleContext *ttc, int attribute);
109extern void toast_tuple_externalize(ToastTupleContext *ttc, int attribute,
110 int options);
111extern void toast_tuple_cleanup(ToastTupleContext *ttc);
112
113extern void toast_delete_external(Relation rel, const Datum *values, const bool *isnull,
114 bool is_speculative);
115
116#endif
static Datum values[MAXATTR]
Definition: bootstrap.c:153
uint8_t uint8
Definition: c.h:536
int32_t int32
Definition: c.h:534
uint64_t Datum
Definition: postgres.h:70
Definition: rel.h:56
uint8 tai_colflags
Definition: toast_helper.h:34
int32 tai_size
Definition: toast_helper.h:33
struct varlena * tai_oldexternal
Definition: toast_helper.h:32
char tai_compression
Definition: toast_helper.h:35
Datum * ttc_values
Definition: toast_helper.h:50
Relation ttc_rel
Definition: toast_helper.h:49
ToastAttrInfo * ttc_attr
Definition: toast_helper.h:62
bool * ttc_isnull
Definition: toast_helper.h:51
bool * ttc_oldisnull
Definition: toast_helper.h:53
Datum * ttc_oldvalues
Definition: toast_helper.h:52
Definition: oid2name.c:30
Definition: c.h:692
void toast_tuple_init(ToastTupleContext *ttc)
Definition: toast_helper.c:41
void toast_delete_external(Relation rel, const Datum *values, const bool *isnull, bool is_speculative)
Definition: toast_helper.c:318
void toast_tuple_try_compression(ToastTupleContext *ttc, int attribute)
Definition: toast_helper.c:227
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
int toast_tuple_find_biggest_attribute(ToastTupleContext *ttc, bool for_compression, bool check_main)
Definition: toast_helper.c:181

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