Adding upstream version 15.5.upstream/15.5

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 282 insertions, 0 deletions

diff --git a/src/include/catalog/pg_statistic.h b/src/include/catalog/pg_statistic.h
new file mode 100644
index 0000000..cdf7448
--- /dev/null
+++ b/src/include/catalog/pg_statistic.h
@@ -0,0 +1,282 @@
+/*-------------------------------------------------------------------------
+ *
+ * pg_statistic.h
+ *	  definition of the "statistics" system catalog (pg_statistic)
+ *
+ *
+ * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/catalog/pg_statistic.h
+ *
+ * NOTES
+ *	  The Catalog.pm module reads this file and derives schema
+ *	  information.
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef PG_STATISTIC_H
+#define PG_STATISTIC_H
+
+#include "catalog/genbki.h"
+#include "catalog/pg_statistic_d.h"
+
+/* ----------------
+ *		pg_statistic definition.  cpp turns this into
+ *		typedef struct FormData_pg_statistic
+ * ----------------
+ */
+CATALOG(pg_statistic,2619,StatisticRelationId)
+{
+	/* These fields form the unique key for the entry: */
+	Oid			starelid BKI_LOOKUP(pg_class);	/* relation containing
+												 * attribute */
+	int16		staattnum;		/* attribute (column) stats are for */
+	bool		stainherit;		/* true if inheritance children are included */
+
+	/* the fraction of the column's entries that are NULL: */
+	float4		stanullfrac;
+
+	/*
+	 * 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
+	 * 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.
+	 */
+	int32		stawidth;
+
+	/* ----------------
+	 * stadistinct indicates the (approximate) number of distinct non-null
+	 * data values in the column.  The interpretation is:
+	 *		0		unknown or not computed
+	 *		> 0		actual number of distinct values
+	 *		< 0		negative of multiplier for number of rows
+	 * The special negative case allows us to cope with columns that are
+	 * unique (stadistinct = -1) or nearly so (for example, a column in which
+	 * non-null values appear about twice on the average could be represented
+	 * by stadistinct = -0.5 if there are no nulls, or -0.4 if 20% of the
+	 * column is nulls).  Because the number-of-rows statistic in pg_class may
+	 * be updated more frequently than pg_statistic is, it's important to be
+	 * able to describe such situations as a multiple of the number of rows,
+	 * rather than a fixed number of distinct values.  But in other cases a
+	 * fixed number is correct (eg, a boolean column).
+	 * ----------------
+	 */
+	float4		stadistinct;
+
+	/* ----------------
+	 * To allow keeping statistics on different kinds of datatypes,
+	 * we do not hard-wire any particular meaning for the remaining
+	 * statistical fields.  Instead, we provide several "slots" in which
+	 * statistical data can be placed.  Each slot includes:
+	 *		kind			integer code identifying kind of data (see below)
+	 *		op				OID of associated operator, if needed
+	 *		coll			OID of relevant collation, or 0 if none
+	 *		numbers			float4 array (for statistical values)
+	 *		values			anyarray (for representations of data values)
+	 * The ID, operator, and collation 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 no need for one or the other.
+	 * ----------------
+	 */
+
+	int16		stakind1;
+	int16		stakind2;
+	int16		stakind3;
+	int16		stakind4;
+	int16		stakind5;
+
+	Oid			staop1 BKI_LOOKUP_OPT(pg_operator);
+	Oid			staop2 BKI_LOOKUP_OPT(pg_operator);
+	Oid			staop3 BKI_LOOKUP_OPT(pg_operator);
+	Oid			staop4 BKI_LOOKUP_OPT(pg_operator);
+	Oid			staop5 BKI_LOOKUP_OPT(pg_operator);
+
+	Oid			stacoll1 BKI_LOOKUP_OPT(pg_collation);
+	Oid			stacoll2 BKI_LOOKUP_OPT(pg_collation);
+	Oid			stacoll3 BKI_LOOKUP_OPT(pg_collation);
+	Oid			stacoll4 BKI_LOOKUP_OPT(pg_collation);
+	Oid			stacoll5 BKI_LOOKUP_OPT(pg_collation);
+
+#ifdef CATALOG_VARLEN			/* variable-length fields start here */
+	float4		stanumbers1[1];
+	float4		stanumbers2[1];
+	float4		stanumbers3[1];
+	float4		stanumbers4[1];
+	float4		stanumbers5[1];
+
+	/*
+	 * Values in these arrays are values of the column's data type, or of some
+	 * related type such as an array element 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.
+	 */
+	anyarray	stavalues1;
+	anyarray	stavalues2;
+	anyarray	stavalues3;
+	anyarray	stavalues4;
+	anyarray	stavalues5;
+#endif
+} FormData_pg_statistic;
+
+#define STATISTIC_NUM_SLOTS  5
+
+
+/* ----------------
+ *		Form_pg_statistic corresponds to a pointer to a tuple with
+ *		the format of pg_statistic relation.
+ * ----------------
+ */
+typedef FormData_pg_statistic *Form_pg_statistic;
+
+DECLARE_TOAST(pg_statistic, 2840, 2841);
+
+DECLARE_UNIQUE_INDEX_PKEY(pg_statistic_relid_att_inh_index, 2696, StatisticRelidAttnumInhIndexId, on pg_statistic using btree(starelid oid_ops, staattnum int2_ops, stainherit bool_ops));
+
+DECLARE_FOREIGN_KEY((starelid, staattnum), pg_attribute, (attrelid, attnum));
+
+#ifdef EXPOSE_TO_CLIENT_CODE
+
+/*
+ * Several statistical slot "kinds" are defined by core PostgreSQL, as
+ * documented below.  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.  (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.
+ */
+
+/*
+ * In a "most common values" slot, staop is the OID of the "=" operator
+ * used to decide whether values are the same or not, and stacoll is the
+ * collation used (same as column's collation).  stavalues contains
+ * the K most common non-null values appearing in the column, and stanumbers
+ * contains their frequencies (fractions of total row count).  The values
+ * shall be ordered in decreasing frequency.  Note that since the arrays are
+ * variable-size, K may be chosen by the statistics collector.  Values should
+ * not appear in MCV unless they have been observed to occur more than once;
+ * a unique column will have no MCV slot.
+ */
+#define STATISTIC_KIND_MCV	1
+
+/*
+ * A "histogram" slot describes the distribution of scalar data.  staop is
+ * the OID of the "<" operator that describes the sort ordering, and stacoll
+ * is the relevant collation.  (In theory more than one histogram could appear,
+ * if a datatype has more than one useful sort operator or we care about more
+ * than one collation.  Currently the collation will always be that of the
+ * underlying column.)  stavalues contains M (>=2) non-null values that
+ * divide the non-null column data values into M-1 bins of approximately equal
+ * population.  The first stavalues item is the MIN and the last is the MAX.
+ * stanumbers is not used and should be NULL.  IMPORTANT POINT: if an MCV
+ * slot is also provided, then the histogram describes the data distribution
+ * *after removing the values listed in MCV* (thus, it's a "compressed
+ * histogram" in the technical parlance).  This allows a more accurate
+ * representation of the distribution of a column with some very-common
+ * values.  In a column with only a few distinct values, it's possible that
+ * the MCV list describes the entire data population; in this case the
+ * histogram reduces to empty and should be omitted.
+ */
+#define STATISTIC_KIND_HISTOGRAM  2
+
+/*
+ * A "correlation" slot describes the correlation between the physical order
+ * of table tuples and the ordering of data values of this column, as seen
+ * by the "<" operator identified by staop with the collation identified by
+ * stacoll.  (As with the histogram, more than one entry could theoretically
+ * appear.)  stavalues is not used and should be NULL.  stanumbers contains
+ * a single entry, the correlation coefficient between the sequence of data
+ * values and the sequence of their actual tuple positions.  The coefficient
+ * ranges from +1 to -1.
+ */
+#define STATISTIC_KIND_CORRELATION	3
+
+/*
+ * 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, and stacoll
+ * contains the collation to use with it.  stavalues contains
+ * the most common element values, and stanumbers their frequencies.  Unlike
+ * MCV slots, frequencies are measured as the fraction of non-null rows the
+ * element value appears in, not the frequency of all rows.  Also unlike
+ * MCV slots, the values are sorted into the element type's default order
+ * (to support binary search for a particular value).  Since this puts the
+ * minimum and maximum frequencies at unpredictable spots in stanumbers,
+ * there are two extra members of stanumbers, holding copies of the minimum
+ * and maximum frequencies.  Optionally, there can be a third extra member,
+ * which holds the frequency of null elements (expressed in the same terms:
+ * the fraction of non-null rows that contain at least one null element).  If
+ * this member is omitted, the column is presumed to contain no null elements.
+ *
+ * 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
+
+/*
+ * A "distinct elements count histogram" slot describes the distribution of
+ * the number of distinct element values present in each row of an array-type
+ * column.  Only non-null rows are considered, and only non-null elements.
+ * staop contains the equality operator appropriate to the element type,
+ * and stacoll contains the collation to use with it.
+ * stavalues is not used and should be NULL.  The last member of stanumbers is
+ * the average count of distinct element values over all non-null rows.  The
+ * preceding M (>=2) members form a histogram that divides the population of
+ * distinct-elements counts into M-1 bins of approximately equal population.
+ * The first of these is the minimum observed count, and the last the maximum.
+ */
+#define STATISTIC_KIND_DECHIST	5
+
+/*
+ * A "length histogram" slot describes the distribution of range lengths in
+ * rows of a range-type column. stanumbers contains a single entry, the
+ * fraction of empty ranges. stavalues is a histogram of non-empty lengths, in
+ * a format similar to STATISTIC_KIND_HISTOGRAM: it contains M (>=2) range
+ * values that divide the column data values into M-1 bins of approximately
+ * equal population. The lengths are stored as float8s, as measured by the
+ * range type's subdiff function. Only non-null rows are considered.
+ */
+#define STATISTIC_KIND_RANGE_LENGTH_HISTOGRAM  6
+
+/*
+ * A "bounds histogram" slot is similar to STATISTIC_KIND_HISTOGRAM, but for
+ * a range-type column.  stavalues contains M (>=2) range values that divide
+ * the column data values into M-1 bins of approximately equal population.
+ * Unlike a regular scalar histogram, this is actually two histograms combined
+ * into a single array, with the lower bounds of each value forming a
+ * histogram of lower bounds, and the upper bounds a histogram of upper
+ * bounds.  Only non-NULL, non-empty ranges are included.
+ */
+#define STATISTIC_KIND_BOUNDS_HISTOGRAM  7
+
+#endif							/* EXPOSE_TO_CLIENT_CODE */
+
+#endif							/* PG_STATISTIC_H */