X-Git-Url: https://granicus.if.org/sourcecode?a=blobdiff_plain;f=src%2Finclude%2Fcatalog%2Fpg_statistic.h;h=0ca66edd7f8c9c48b30f422fdfbd9de527868df2;hb=6f6d8632583353d60fe3bb1694b39f6124f6e5d1;hp=920e29c4396686803947f8b78838618315bfebfc;hpb=b81844b1738c584d92330a5ccd0fbd8b603d2886;p=postgresql diff --git a/src/include/catalog/pg_statistic.h b/src/include/catalog/pg_statistic.h index 920e29c439..0ca66edd7f 100644 --- a/src/include/catalog/pg_statistic.h +++ b/src/include/catalog/pg_statistic.h @@ -5,10 +5,10 @@ * along with the relation's initial contents. * * - * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group + * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $Id: pg_statistic.h,v 1.13 2001/10/25 05:49:58 momjian Exp $ + * $PostgreSQL: pgsql/src/include/catalog/pg_statistic.h,v 1.36 2008/07/14 00:51:45 tgl Exp $ * * NOTES * the genbki.sh script reads this file and generates .bki @@ -19,19 +19,26 @@ #ifndef PG_STATISTIC_H #define PG_STATISTIC_H -/* ---------------- - * postgres.h contains the system type definintions and the - * CATALOG(), BOOTSTRAP and DATA() sugar words so this file - * can be read by both genbki.sh and the C compiler. - * ---------------- +#include "catalog/genbki.h" + +/* + * The CATALOG definition has to refer to the type of stavaluesN as + * "anyarray" so that bootstrap mode recognizes it. There is no real + * typedef for that, however. Since the fields are potentially-null and + * therefore can't be accessed directly from C code, there is no particular + * need for the C struct definition to show a valid field type --- instead + * we just make it int. */ +#define anyarray int /* ---------------- * pg_statistic definition. cpp turns this into * typedef struct FormData_pg_statistic * ---------------- */ -CATALOG(pg_statistic) BKI_WITHOUT_OIDS +#define StatisticRelationId 2619 + +CATALOG(pg_statistic,2619) BKI_WITHOUT_OIDS { /* These fields form the unique key for the entry: */ Oid starelid; /* relation containing attribute */ @@ -42,13 +49,13 @@ CATALOG(pg_statistic) BKI_WITHOUT_OIDS /* * stawidth is the average width in bytes of non-null entries. For - * fixed-width datatypes this is of course the same as the typlen, but - * for varlena types it is more useful. Note that this is the average - * width of the data as actually stored, post-TOASTing (eg, for a + * fixed-width datatypes this is of course the same as the typlen, but for + * var-width types it is more useful. Note that this is the average width + * of the data as actually stored, post-TOASTing (eg, for a * moved-out-of-line value, only the size of the pointer object is - * counted). This is the appropriate definition for the primary use - * of the statistic, which is to estimate sizes of in-memory hash - * tables of tuples. + * counted). This is the appropriate definition for the primary use of + * the statistic, which is to estimate sizes of in-memory hash tables of + * tuples. */ int4 stawidth; @@ -78,7 +85,7 @@ CATALOG(pg_statistic) BKI_WITHOUT_OIDS * kind integer code identifying kind of data * op OID of associated operator, if needed * numbers float4 array (for statistical values) - * values text array (for representations of data values) + * values anyarray (for representations of data values) * The ID and operator fields are never NULL; they are zeroes in an * unused slot. The numbers and values fields are NULL in an unused * slot, and might also be NULL in a used slot if the slot kind has @@ -97,10 +104,10 @@ CATALOG(pg_statistic) BKI_WITHOUT_OIDS Oid staop4; /* - * THE REST OF THESE ARE VARIABLE LENGTH FIELDS, and may even be - * absent (NULL). They cannot be accessed as C struct entries; you - * have to use the full field access machinery (heap_getattr) for - * them. We declare them here for the catalog machinery. + * THE REST OF THESE ARE VARIABLE LENGTH FIELDS, and may even be absent + * (NULL). They cannot be accessed as C struct entries; you have to use + * the full field access machinery (heap_getattr) for them. We declare + * them here for the catalog machinery. */ float4 stanumbers1[1]; @@ -109,18 +116,21 @@ CATALOG(pg_statistic) BKI_WITHOUT_OIDS float4 stanumbers4[1]; /* - * Values in these text arrays are external representations of values - * of the column's data type. To re-create the actual Datum, do - * datatypein(textout(arrayelement)). + * Values in these arrays are values of the column's data type. We + * presently have to cheat quite a bit to allow polymorphic arrays of this + * kind, but perhaps someday it'll be a less bogus facility. */ - text stavalues1[1]; - text stavalues2[1]; - text stavalues3[1]; - text stavalues4[1]; + anyarray stavalues1; + anyarray stavalues2; + anyarray stavalues3; + anyarray stavalues4; } FormData_pg_statistic; #define STATISTIC_NUM_SLOTS 4 +#undef anyarray + + /* ---------------- * Form_pg_statistic corresponds to a pointer to a tuple with * the format of pg_statistic relation. @@ -158,11 +168,32 @@ typedef FormData_pg_statistic *Form_pg_statistic; /* * Currently, three statistical slot "kinds" are defined: most common values, * histogram, and correlation. Additional "kinds" will probably appear in - * future to help cope with non-scalar datatypes. + * future to help cope with non-scalar datatypes. Also, custom data types + * can define their own "kind" codes by mutual agreement between a custom + * typanalyze routine and the selectivity estimation functions of the type's + * operators. * * Code reading the pg_statistic relation should not assume that a particular * data "kind" will appear in any particular slot. Instead, search the - * stakind fields to see if the desired data is available. + * stakind fields to see if the desired data is available. (The standard + * function get_attstatsslot() may be used for this.) + */ + +/* + * The present allocation of "kind" codes is: + * + * 1-99: reserved for assignment by the core PostgreSQL project + * (values in this range will be documented in this file) + * 100-199: reserved for assignment by the PostGIS project + * (values to be documented in PostGIS documentation) + * 200-299: reserved for assignment by the ESRI ST_Geometry project + * (values to be documented in ESRI ST_Geometry documentation) + * 300-9999: reserved for future public assignments + * + * For private use you may choose a "kind" code at random in the range + * 10000-30000. However, for code that is to be widely disseminated it is + * better to obtain a publicly defined "kind" code by request from the + * PostgreSQL Global Development Group. */ /* @@ -205,4 +236,20 @@ typedef FormData_pg_statistic *Form_pg_statistic; * their actual tuple positions. The coefficient ranges from +1 to -1. */ #define STATISTIC_KIND_CORRELATION 3 -#endif /* PG_STATISTIC_H */ + +/* + * A "most common elements" slot is similar to a "most common values" slot, + * except that it stores the most common non-null *elements* of the column + * values. This is useful when the column datatype is an array or some other + * type with identifiable elements (for instance, tsvector). staop contains + * the equality operator appropriate to the element type. stavalues contains + * the most common element values, and stanumbers their frequencies, with the + * same rules as for MCV slots. + * + * Note: in current usage for tsvector columns, the stavalues elements are of + * type text, even though their representation within tsvector is not + * exactly text. + */ +#define STATISTIC_KIND_MCELEM 4 + +#endif /* PG_STATISTIC_H */