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95 lines
3.0 KiB
C
95 lines
3.0 KiB
C
/*-------------------------------------------------------------------------
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*
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* pg_statistic.h
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* definition of the system "statistic" relation (pg_statistic)
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* along with the relation's initial contents.
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*
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*
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* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $Id: pg_statistic.h,v 1.9 2000/04/12 17:16:29 momjian Exp $
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*
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* NOTES
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* the genbki.sh script reads this file and generates .bki
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* information from the DATA() statements.
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef PG_STATISTIC_H
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#define PG_STATISTIC_H
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/* ----------------
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* postgres.h contains the system type definintions and the
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* CATALOG(), BOOTSTRAP and DATA() sugar words so this file
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* can be read by both genbki.sh and the C compiler.
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* ----------------
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*/
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/* ----------------
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* pg_statistic definition. cpp turns this into
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* typedef struct FormData_pg_statistic
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* ----------------
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*/
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CATALOG(pg_statistic)
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{
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/* These fields form the unique key for the entry: */
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Oid starelid; /* relation containing attribute */
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int2 staattnum; /* attribute (column) stats are for */
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Oid staop; /* '<' comparison op used for lo/hi vals */
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/*
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* Note: the current VACUUM code will never produce more than one
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* entry per column, but in theory there could be multiple entries if
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* a datatype has more than one useful ordering operator. Also, the
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* current code will not write an entry unless it found at least one
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* non-NULL value in the column; so the remaining fields will never be
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* NULL.
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*/
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/*
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* These fields contain the stats about the column indicated by the
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* key
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*/
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float4 stanullfrac; /* the fraction of the entries that are
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* NULL */
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float4 stacommonfrac; /* the fraction that are the most common
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* val */
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/*
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* THE REST OF THESE ARE VARIABLE LENGTH FIELDS. They cannot be
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* accessed as C struct entries; you have to use the full field access
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* machinery (heap_getattr) for them.
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*
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* All three of these are text representations of data values of the
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* column's data type. To re-create the actual Datum, do
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* datatypein(textout(givenvalue)).
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*/
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text stacommonval; /* most common non-null value in column */
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text staloval; /* smallest non-null value in column */
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text stahival; /* largest non-null value in column */
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} FormData_pg_statistic;
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/* ----------------
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* Form_pg_statistic corresponds to a pointer to a tuple with
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* the format of pg_statistic relation.
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* ----------------
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*/
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typedef FormData_pg_statistic *Form_pg_statistic;
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/* ----------------
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* compiler constants for pg_statistic
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* ----------------
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*/
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#define Natts_pg_statistic 8
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#define Anum_pg_statistic_starelid 1
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#define Anum_pg_statistic_staattnum 2
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#define Anum_pg_statistic_staop 3
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#define Anum_pg_statistic_stanullfrac 4
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#define Anum_pg_statistic_stacommonfrac 5
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#define Anum_pg_statistic_stacommonval 6
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#define Anum_pg_statistic_staloval 7
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#define Anum_pg_statistic_stahival 8
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#endif /* PG_STATISTIC_H */
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