time_analyze.c File Reference

Functions for gathering statistics from time type columns. More...

#include "general/time_analyze.h"
#include <assert.h>
#include <catalog/pg_operator.h>
#include <commands/vacuum.h>
#include "general/timestampset.h"
#include "general/period.h"
#include "general/periodset.h"
#include "general/temporal.h"
#include "general/tempcache.h"

Include dependency graph for time_analyze.c:

Functions
static void	timetype_compute_stats (CachedType timetype, VacAttrStats *stats, AnalyzeAttrFetchFunc fetchfunc, int samplerows)
	Compute statistics for timestamp set, period, and period set columns. More...
static void	period_compute_stats (VacAttrStats *stats, AnalyzeAttrFetchFunc fetchfunc, int samplerows, double totalrows)
	Compute statistics for period columns (callback function) More...
static void	timestampset_compute_stats (VacAttrStats *stats, AnalyzeAttrFetchFunc fetchfunc, int samplerows, double totalrows)
	Compute statistics for timestampset columns (callback function) More...
static void	periodset_compute_stats (VacAttrStats *stats, AnalyzeAttrFetchFunc fetchfunc, int samplerows, double totalrows)
	Compute statistics for period set columns (callback function) More...
int	float8_qsort_cmp (const void *a1, const void *a2)
	Comparison function for sorting float8 values, used for period lengths. More...
void	period_compute_stats1 (VacAttrStats *stats, int non_null_cnt, int *slot_idx, PeriodBound *lowers, PeriodBound *uppers, float8 *lengths)
	Compute statistics for period columns and for the time dimension of all temporal types whose subtype is not instant. More...
PGDLLEXPORT Datum	period_analyze (PG_FUNCTION_ARGS)
	Compute statistics for period columns. More...
PGDLLEXPORT Datum	timestampset_analyze (PG_FUNCTION_ARGS)
	Compute statistics for timestamp set columns. More...
PGDLLEXPORT Datum	periodset_analyze (PG_FUNCTION_ARGS)
	Compute statistics for period set columns. More...

Detailed Description

Functions for gathering statistics from time type columns.

These functions are based on those of the file rangetypes_typanalyze.c. For a period type column, histograms of lower and upper bounds, and the fraction of NULL periods are collected.

Both histograms have the same length, and they are combined into a single array of periods. This has the same shape as the histogram that std_typanalyze would collect, but the values are different. Each period in the array is a valid period, even though the lower and upper bounds come from different tuples. In theory, the standard scalar selectivity functions could be used with the combined histogram.