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pg_attribute.h
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1 /*-------------------------------------------------------------------------
2  *
3  * pg_attribute.h
4  * definition of the "attribute" system catalog (pg_attribute)
5  *
6  * The initial contents of pg_attribute are generated at compile time by
7  * genbki.pl, so there is no pg_attribute.dat file. Only "bootstrapped"
8  * relations need be included.
9  *
10  *
11  * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
12  * Portions Copyright (c) 1994, Regents of the University of California
13  *
14  * src/include/catalog/pg_attribute.h
15  *
16  * NOTES
17  * The Catalog.pm module reads this file and derives schema
18  * information.
19  *
20  *-------------------------------------------------------------------------
21  */
22 #ifndef PG_ATTRIBUTE_H
23 #define PG_ATTRIBUTE_H
24 
25 #include "catalog/genbki.h"
26 #include "catalog/pg_attribute_d.h"
27 
28 /* ----------------
29  * pg_attribute definition. cpp turns this into
30  * typedef struct FormData_pg_attribute
31  *
32  * If you change the following, make sure you change the structs for
33  * system attributes in catalog/heap.c also.
34  * You may need to change catalog/genbki.pl as well.
35  * ----------------
36  */
37 CATALOG(pg_attribute,1249,AttributeRelationId) BKI_BOOTSTRAP BKI_ROWTYPE_OID(75,AttributeRelation_Rowtype_Id) BKI_SCHEMA_MACRO
38 {
39  Oid attrelid BKI_LOOKUP(pg_class); /* OID of relation containing
40  * this attribute */
41  NameData attname; /* name of attribute */
42 
43  /*
44  * atttypid is the OID of the instance in Catalog Class pg_type that
45  * defines the data type of this attribute (e.g. int4). Information in
46  * that instance is redundant with the attlen, attbyval, and attalign
47  * attributes of this instance, so they had better match or Postgres will
48  * fail. In an entry for a dropped column, this field is set to zero
49  * since the pg_type entry may no longer exist; but we rely on attlen,
50  * attbyval, and attalign to still tell us how large the values in the
51  * table are.
52  */
53  Oid atttypid BKI_LOOKUP_OPT(pg_type);
54 
55  /*
56  * attstattarget is the target number of statistics datapoints to collect
57  * during VACUUM ANALYZE of this column. A zero here indicates that we do
58  * not wish to collect any stats about this column. A "-1" here indicates
59  * that no value has been explicitly set for this column, so ANALYZE
60  * should use the default setting.
61  */
62  int32 attstattarget BKI_DEFAULT(-1);
63 
64  /*
65  * attlen is a copy of the typlen field from pg_type for this attribute.
66  * See atttypid comments above.
67  */
69 
70  /*
71  * attnum is the "attribute number" for the attribute: A value that
72  * uniquely identifies this attribute within its class. For user
73  * attributes, Attribute numbers are greater than 0 and not greater than
74  * the number of attributes in the class. I.e. if the Class pg_class says
75  * that Class XYZ has 10 attributes, then the user attribute numbers in
76  * Class pg_attribute must be 1-10.
77  *
78  * System attributes have attribute numbers less than 0 that are unique
79  * within the class, but not constrained to any particular range.
80  *
81  * Note that (attnum - 1) is often used as the index to an array.
82  */
84 
85  /*
86  * attndims is the declared number of dimensions, if an array type,
87  * otherwise zero.
88  */
90 
91  /*
92  * fastgetattr() uses attcacheoff to cache byte offsets of attributes in
93  * heap tuples. The value actually stored in pg_attribute (-1) indicates
94  * no cached value. But when we copy these tuples into a tuple
95  * descriptor, we may then update attcacheoff in the copies. This speeds
96  * up the attribute walking process.
97  */
98  int32 attcacheoff BKI_DEFAULT(-1);
99 
100  /*
101  * atttypmod records type-specific data supplied at table creation time
102  * (for example, the max length of a varchar field). It is passed to
103  * type-specific input and output functions as the third argument. The
104  * value will generally be -1 for types that do not need typmod.
105  */
106  int32 atttypmod BKI_DEFAULT(-1);
107 
108  /*
109  * attbyval is a copy of the typbyval field from pg_type for this
110  * attribute. See atttypid comments above.
111  */
112  bool attbyval;
113 
114  /*
115  * attalign is a copy of the typalign field from pg_type for this
116  * attribute. See atttypid comments above.
117  */
118  char attalign;
119 
120  /*----------
121  * attstorage tells for VARLENA attributes, what the heap access
122  * methods can do to it if a given tuple doesn't fit into a page.
123  * Possible values are as for pg_type.typstorage (see TYPSTORAGE macros).
124  *----------
125  */
127 
128  /*
129  * attcompression sets the current compression method of the attribute.
130  * Typically this is InvalidCompressionMethod ('\0') to specify use of the
131  * current default setting (see default_toast_compression). Otherwise,
132  * 'p' selects pglz compression, while 'l' selects LZ4 compression.
133  * However, this field is ignored whenever attstorage does not allow
134  * compression.
135  */
136  char attcompression BKI_DEFAULT('\0');
137 
138  /* This flag represents the "NOT NULL" constraint */
140 
141  /* Has DEFAULT value or not */
142  bool atthasdef BKI_DEFAULT(f);
143 
144  /* Has a missing value or not */
145  bool atthasmissing BKI_DEFAULT(f);
146 
147  /* One of the ATTRIBUTE_IDENTITY_* constants below, or '\0' */
148  char attidentity BKI_DEFAULT('\0');
149 
150  /* One of the ATTRIBUTE_GENERATED_* constants below, or '\0' */
151  char attgenerated BKI_DEFAULT('\0');
152 
153  /* Is dropped (ie, logically invisible) or not */
154  bool attisdropped BKI_DEFAULT(f);
155 
156  /*
157  * This flag specifies whether this column has ever had a local
158  * definition. It is set for normal non-inherited columns, but also for
159  * columns that are inherited from parents if also explicitly listed in
160  * CREATE TABLE INHERITS. It is also set when inheritance is removed from
161  * a table with ALTER TABLE NO INHERIT. If the flag is set, the column is
162  * not dropped by a parent's DROP COLUMN even if this causes the column's
163  * attinhcount to become zero.
164  */
165  bool attislocal BKI_DEFAULT(t);
166 
167  /* Number of times inherited from direct parent relation(s) */
168  int32 attinhcount BKI_DEFAULT(0);
169 
170  /* attribute's collation, if any */
171  Oid attcollation BKI_LOOKUP_OPT(pg_collation);
172 
173 #ifdef CATALOG_VARLEN /* variable-length fields start here */
174  /* NOTE: The following fields are not present in tuple descriptors. */
175 
176  /* Column-level access permissions */
177  aclitem attacl[1] BKI_DEFAULT(_null_);
178 
179  /* Column-level options */
180  text attoptions[1] BKI_DEFAULT(_null_);
181 
182  /* Column-level FDW options */
183  text attfdwoptions[1] BKI_DEFAULT(_null_);
184 
185  /*
186  * Missing value for added columns. This is a one element array which lets
187  * us store a value of the attribute type here.
188  */
189  anyarray attmissingval BKI_DEFAULT(_null_);
190 #endif
192 
193 /*
194  * ATTRIBUTE_FIXED_PART_SIZE is the size of the fixed-layout,
195  * guaranteed-not-null part of a pg_attribute row. This is in fact as much
196  * of the row as gets copied into tuple descriptors, so don't expect you
197  * can access the variable-length fields except in a real tuple!
198  */
199 #define ATTRIBUTE_FIXED_PART_SIZE \
200  (offsetof(FormData_pg_attribute,attcollation) + sizeof(Oid))
201 
202 /* ----------------
203  * Form_pg_attribute corresponds to a pointer to a tuple with
204  * the format of pg_attribute relation.
205  * ----------------
206  */
208 
209 DECLARE_UNIQUE_INDEX(pg_attribute_relid_attnam_index, 2658, AttributeRelidNameIndexId, on pg_attribute using btree(attrelid oid_ops, attname name_ops));
210 DECLARE_UNIQUE_INDEX_PKEY(pg_attribute_relid_attnum_index, 2659, AttributeRelidNumIndexId, on pg_attribute using btree(attrelid oid_ops, attnum int2_ops));
211 
212 #ifdef EXPOSE_TO_CLIENT_CODE
213 
214 #define ATTRIBUTE_IDENTITY_ALWAYS 'a'
215 #define ATTRIBUTE_IDENTITY_BY_DEFAULT 'd'
216 
217 #define ATTRIBUTE_GENERATED_STORED 's'
218 
219 #endif /* EXPOSE_TO_CLIENT_CODE */
220 
221 #endif /* PG_ATTRIBUTE_H */
#define BKI_BOOTSTRAP
Definition: genbki.h:26
signed short int16
Definition: c.h:428
char attstorage
Definition: pg_attribute.h:126
bool attnotnull
Definition: pg_attribute.h:139
CATALOG(pg_attribute, 1249, AttributeRelationId) BKI_BOOTSTRAP BKI_ROWTYPE_OID(75
unsigned int Oid
Definition: postgres_ext.h:31
signed int int32
Definition: c.h:429
bool attbyval
Definition: pg_attribute.h:112
NameData attname
Definition: pg_attribute.h:41
AttributeRelation_Rowtype_Id BKI_SCHEMA_MACRO
Definition: pg_attribute.h:38
Definition: c.h:675
char attalign
Definition: pg_attribute.h:118
FormData_pg_attribute * Form_pg_attribute
Definition: pg_attribute.h:207
#define BKI_LOOKUP(catalog)
Definition: genbki.h:46
#define BKI_ROWTYPE_OID(oid, oidmacro)
Definition: genbki.h:28
int16 attlen
Definition: pg_attribute.h:68
int32 attstattarget BKI_DEFAULT(-1)
int32 attndims
Definition: pg_attribute.h:89
FormData_pg_attribute
Definition: pg_attribute.h:191
int16 attnum
Definition: pg_attribute.h:83
DECLARE_UNIQUE_INDEX(pg_attribute_relid_attnam_index, 2658, AttributeRelidNameIndexId, on pg_attribute using btree(attrelid oid_ops, attname name_ops))
Oid atttypid BKI_LOOKUP_OPT(pg_type)
Definition: c.h:621
DECLARE_UNIQUE_INDEX_PKEY(pg_attribute_relid_attnum_index, 2659, AttributeRelidNumIndexId, on pg_attribute using btree(attrelid oid_ops, attnum int2_ops))