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pg_statistic.h File Reference
#include "catalog/genbki.h"
#include "catalog/pg_statistic_d.h"
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Macros

#define STATISTIC_NUM_SLOTS   5
 
#define StatisticRelidAttnumInhIndexId   2696
 

Typedefs

typedef FormData_pg_statisticForm_pg_statistic
 

Functions

 CATALOG (pg_statistic, 2619, StatisticRelationId)
 
 DECLARE_TOAST (pg_statistic, 2840, 2841)
 
 DECLARE_UNIQUE_INDEX_PKEY (pg_statistic_relid_att_inh_index, 2696, on pg_statistic using btree(starelid oid_ops, staattnum int2_ops, stainherit bool_ops))
 
 DECLARE_FOREIGN_KEY ((starelid, staattnum), pg_attribute,(attrelid, attnum))
 

Variables

 FormData_pg_statistic
 

Macro Definition Documentation

◆ STATISTIC_NUM_SLOTS

#define STATISTIC_NUM_SLOTS   5

◆ StatisticRelidAttnumInhIndexId

#define StatisticRelidAttnumInhIndexId   2696

Definition at line 140 of file pg_statistic.h.

Referenced by CopyStatistics(), and RemoveStatistics().

Typedef Documentation

◆ Form_pg_statistic

Definition at line 135 of file pg_statistic.h.

Function Documentation

◆ CATALOG()

CATALOG ( pg_statistic  ,
2619  ,
StatisticRelationId   
)

Definition at line 29 of file pg_statistic.h.

References BKI_LOOKUP, and BKI_LOOKUP_OPT.

30 {
31  /* These fields form the unique key for the entry: */
32  Oid starelid BKI_LOOKUP(pg_class); /* relation containing
33  * attribute */
34  int16 staattnum; /* attribute (column) stats are for */
35  bool stainherit; /* true if inheritance children are included */
36 
37  /* the fraction of the column's entries that are NULL: */
38  float4 stanullfrac;
39 
40  /*
41  * stawidth is the average width in bytes of non-null entries. For
42  * fixed-width datatypes this is of course the same as the typlen, but for
43  * var-width types it is more useful. Note that this is the average width
44  * of the data as actually stored, post-TOASTing (eg, for a
45  * moved-out-of-line value, only the size of the pointer object is
46  * counted). This is the appropriate definition for the primary use of
47  * the statistic, which is to estimate sizes of in-memory hash tables of
48  * tuples.
49  */
50  int32 stawidth;
51 
52  /* ----------------
53  * stadistinct indicates the (approximate) number of distinct non-null
54  * data values in the column. The interpretation is:
55  * 0 unknown or not computed
56  * > 0 actual number of distinct values
57  * < 0 negative of multiplier for number of rows
58  * The special negative case allows us to cope with columns that are
59  * unique (stadistinct = -1) or nearly so (for example, a column in which
60  * non-null values appear about twice on the average could be represented
61  * by stadistinct = -0.5 if there are no nulls, or -0.4 if 20% of the
62  * column is nulls). Because the number-of-rows statistic in pg_class may
63  * be updated more frequently than pg_statistic is, it's important to be
64  * able to describe such situations as a multiple of the number of rows,
65  * rather than a fixed number of distinct values. But in other cases a
66  * fixed number is correct (eg, a boolean column).
67  * ----------------
68  */
69  float4 stadistinct;
70 
71  /* ----------------
72  * To allow keeping statistics on different kinds of datatypes,
73  * we do not hard-wire any particular meaning for the remaining
74  * statistical fields. Instead, we provide several "slots" in which
75  * statistical data can be placed. Each slot includes:
76  * kind integer code identifying kind of data (see below)
77  * op OID of associated operator, if needed
78  * coll OID of relevant collation, or 0 if none
79  * numbers float4 array (for statistical values)
80  * values anyarray (for representations of data values)
81  * The ID, operator, and collation fields are never NULL; they are zeroes
82  * in an unused slot. The numbers and values fields are NULL in an
83  * unused slot, and might also be NULL in a used slot if the slot kind
84  * has no need for one or the other.
85  * ----------------
86  */
87 
88  int16 stakind1;
89  int16 stakind2;
90  int16 stakind3;
91  int16 stakind4;
92  int16 stakind5;
93 
94  Oid staop1 BKI_LOOKUP_OPT(pg_operator);
95  Oid staop2 BKI_LOOKUP_OPT(pg_operator);
96  Oid staop3 BKI_LOOKUP_OPT(pg_operator);
97  Oid staop4 BKI_LOOKUP_OPT(pg_operator);
98  Oid staop5 BKI_LOOKUP_OPT(pg_operator);
99 
100  Oid stacoll1 BKI_LOOKUP_OPT(pg_collation);
101  Oid stacoll2 BKI_LOOKUP_OPT(pg_collation);
102  Oid stacoll3 BKI_LOOKUP_OPT(pg_collation);
103  Oid stacoll4 BKI_LOOKUP_OPT(pg_collation);
104  Oid stacoll5 BKI_LOOKUP_OPT(pg_collation);
105 
106 #ifdef CATALOG_VARLEN /* variable-length fields start here */
107  float4 stanumbers1[1];
108  float4 stanumbers2[1];
109  float4 stanumbers3[1];
110  float4 stanumbers4[1];
111  float4 stanumbers5[1];
112 
113  /*
114  * Values in these arrays are values of the column's data type, or of some
115  * related type such as an array element type. We presently have to cheat
116  * quite a bit to allow polymorphic arrays of this kind, but perhaps
117  * someday it'll be a less bogus facility.
118  */
119  anyarray stavalues1;
120  anyarray stavalues2;
121  anyarray stavalues3;
122  anyarray stavalues4;
123  anyarray stavalues5;
124 #endif
signed short int16
Definition: c.h:428
unsigned int Oid
Definition: postgres_ext.h:31
signed int int32
Definition: c.h:429
FormData_pg_statistic
Definition: pg_statistic.h:125
#define BKI_LOOKUP_OPT(catalog)
Definition: genbki.h:47
#define BKI_LOOKUP(catalog)
Definition: genbki.h:46
float float4
Definition: c.h:564

◆ DECLARE_FOREIGN_KEY()

DECLARE_FOREIGN_KEY ( (starelid, staattnum)  ,
pg_attribute  ,
(attrelid, attnum  
)

◆ DECLARE_TOAST()

DECLARE_TOAST ( pg_statistic  ,
2840  ,
2841   
)

◆ DECLARE_UNIQUE_INDEX_PKEY()

DECLARE_UNIQUE_INDEX_PKEY ( pg_statistic_relid_att_inh_index  ,
2696  ,
on pg_statistic using   btreestarelid oid_ops, staattnum int2_ops, stainherit bool_ops 
)

Variable Documentation

◆ FormData_pg_statistic

FormData_pg_statistic

Definition at line 125 of file pg_statistic.h.