PostgreSQL Source Code
git master
Main Page
Related Pages
Namespaces
Namespace List
Namespace Members
All
Functions
Variables
Data Structures
Data Structures
Data Structure Index
Class Hierarchy
Data Fields
All
_
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
t
u
v
w
x
y
z
~
Functions
_
a
f
h
i
n
o
p
r
s
~
Variables
_
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
t
u
v
w
x
y
z
Enumerations
Files
File List
Globals
All
_
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
t
u
v
w
x
y
z
Functions
_
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
t
u
v
w
x
y
z
Variables
_
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
t
u
v
w
x
y
z
Typedefs
_
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
t
u
v
w
x
y
z
Enumerations
_
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
t
u
v
w
x
Enumerator
_
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
t
u
v
w
x
z
Macros
_
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
t
u
v
w
x
y
z
•
All
Data Structures
Namespaces
Files
Functions
Variables
Typedefs
Enumerations
Enumerator
Macros
Pages
itemid.h
Go to the documentation of this file.
1
/*-------------------------------------------------------------------------
2
*
3
* itemid.h
4
* Standard POSTGRES buffer page item identifier/line pointer definitions.
5
*
6
*
7
* Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
8
* Portions Copyright (c) 1994, Regents of the University of California
9
*
10
* src/include/storage/itemid.h
11
*
12
*-------------------------------------------------------------------------
13
*/
14
#ifndef ITEMID_H
15
#define ITEMID_H
16
17
/*
18
* A line pointer on a buffer page. See buffer page definitions and comments
19
* for an explanation of how line pointers are used.
20
*
21
* In some cases a line pointer is "in use" but does not have any associated
22
* storage on the page. By convention, lp_len == 0 in every line pointer
23
* that does not have storage, independently of its lp_flags state.
24
*/
25
typedef
struct
ItemIdData
26
{
27
unsigned
lp_off
:15,
/* offset to tuple (from start of page) */
28
lp_flags
:2,
/* state of line pointer, see below */
29
lp_len
:15;
/* byte length of tuple */
30
}
ItemIdData
;
31
32
typedef
ItemIdData
*
ItemId
;
33
34
/*
35
* lp_flags has these possible states. An UNUSED line pointer is available
36
* for immediate re-use, the other states are not.
37
*/
38
#define LP_UNUSED 0
/* unused (should always have lp_len=0) */
39
#define LP_NORMAL 1
/* used (should always have lp_len>0) */
40
#define LP_REDIRECT 2
/* HOT redirect (should have lp_len=0) */
41
#define LP_DEAD 3
/* dead, may or may not have storage */
42
43
/*
44
* Item offsets and lengths are represented by these types when
45
* they're not actually stored in an ItemIdData.
46
*/
47
typedef
uint16
ItemOffset
;
48
typedef
uint16
ItemLength
;
49
50
51
/* ----------------
52
* support macros
53
* ----------------
54
*/
55
56
/*
57
* ItemIdGetLength
58
*/
59
#define ItemIdGetLength(itemId) \
60
((itemId)->lp_len)
61
62
/*
63
* ItemIdGetOffset
64
*/
65
#define ItemIdGetOffset(itemId) \
66
((itemId)->lp_off)
67
68
/*
69
* ItemIdGetFlags
70
*/
71
#define ItemIdGetFlags(itemId) \
72
((itemId)->lp_flags)
73
74
/*
75
* ItemIdGetRedirect
76
* In a REDIRECT pointer, lp_off holds offset number for next line pointer
77
*/
78
#define ItemIdGetRedirect(itemId) \
79
((itemId)->lp_off)
80
81
/*
82
* ItemIdIsValid
83
* True iff item identifier is valid.
84
* This is a pretty weak test, probably useful only in Asserts.
85
*/
86
#define ItemIdIsValid(itemId) PointerIsValid(itemId)
87
88
/*
89
* ItemIdIsUsed
90
* True iff item identifier is in use.
91
*/
92
#define ItemIdIsUsed(itemId) \
93
((itemId)->lp_flags != LP_UNUSED)
94
95
/*
96
* ItemIdIsNormal
97
* True iff item identifier is in state NORMAL.
98
*/
99
#define ItemIdIsNormal(itemId) \
100
((itemId)->lp_flags == LP_NORMAL)
101
102
/*
103
* ItemIdIsRedirected
104
* True iff item identifier is in state REDIRECT.
105
*/
106
#define ItemIdIsRedirected(itemId) \
107
((itemId)->lp_flags == LP_REDIRECT)
108
109
/*
110
* ItemIdIsDead
111
* True iff item identifier is in state DEAD.
112
*/
113
#define ItemIdIsDead(itemId) \
114
((itemId)->lp_flags == LP_DEAD)
115
116
/*
117
* ItemIdHasStorage
118
* True iff item identifier has associated storage.
119
*/
120
#define ItemIdHasStorage(itemId) \
121
((itemId)->lp_len != 0)
122
123
/*
124
* ItemIdSetUnused
125
* Set the item identifier to be UNUSED, with no storage.
126
* Beware of multiple evaluations of itemId!
127
*/
128
#define ItemIdSetUnused(itemId) \
129
( \
130
(itemId)->lp_flags = LP_UNUSED, \
131
(itemId)->lp_off = 0, \
132
(itemId)->lp_len = 0 \
133
)
134
135
/*
136
* ItemIdSetNormal
137
* Set the item identifier to be NORMAL, with the specified storage.
138
* Beware of multiple evaluations of itemId!
139
*/
140
#define ItemIdSetNormal(itemId, off, len) \
141
( \
142
(itemId)->lp_flags = LP_NORMAL, \
143
(itemId)->lp_off = (off), \
144
(itemId)->lp_len = (len) \
145
)
146
147
/*
148
* ItemIdSetRedirect
149
* Set the item identifier to be REDIRECT, with the specified link.
150
* Beware of multiple evaluations of itemId!
151
*/
152
#define ItemIdSetRedirect(itemId, link) \
153
( \
154
(itemId)->lp_flags = LP_REDIRECT, \
155
(itemId)->lp_off = (link), \
156
(itemId)->lp_len = 0 \
157
)
158
159
/*
160
* ItemIdSetDead
161
* Set the item identifier to be DEAD, with no storage.
162
* Beware of multiple evaluations of itemId!
163
*/
164
#define ItemIdSetDead(itemId) \
165
( \
166
(itemId)->lp_flags = LP_DEAD, \
167
(itemId)->lp_off = 0, \
168
(itemId)->lp_len = 0 \
169
)
170
171
/*
172
* ItemIdMarkDead
173
* Set the item identifier to be DEAD, keeping its existing storage.
174
*
175
* Note: in indexes, this is used as if it were a hint-bit mechanism;
176
* we trust that multiple processors can do this in parallel and get
177
* the same result.
178
*/
179
#define ItemIdMarkDead(itemId) \
180
( \
181
(itemId)->lp_flags = LP_DEAD \
182
)
183
184
#endif
/* ITEMID_H */
uint16
unsigned short uint16
Definition:
c.h:517
ItemOffset
uint16 ItemOffset
Definition:
itemid.h:47
ItemIdData
struct ItemIdData ItemIdData
ItemLength
uint16 ItemLength
Definition:
itemid.h:48
ItemId
ItemIdData * ItemId
Definition:
itemid.h:32
ItemIdData
Definition:
itemid.h:26
ItemIdData::lp_len
unsigned lp_len
Definition:
itemid.h:29
ItemIdData::lp_flags
unsigned lp_flags
Definition:
itemid.h:28
ItemIdData::lp_off
unsigned lp_off
Definition:
itemid.h:27
src
include
storage
itemid.h
Generated on Sat Nov 23 2024 06:13:25 for PostgreSQL Source Code by
1.9.1