Functions for gathering statistics from temporal alphanumeric columns.
Various kind of statistics are collected for both the value and the time dimension of temporal types. Please refer to the PostgreSQL file pg_statistic_d.h for more information about the statistics collected.
- Slot 1
stakind contains the type of statistics which is STATISTIC_KIND_VALUE_BOUNDS_HISTOGRAM.staop contains the "<" operator of the value dimension.stavalues stores the histogram of spans for the value dimension.numvalues contains the number of buckets in the histogram.
- Slot 2
stakind contains the type of statistics which is STATISTIC_KIND_VALUE_LENGTH_HISTOGRAM.staop contains the "<" operator to the value dimension.stavalues stores the length of the histogram of spans for the value dimension.numvalues contains the number of buckets in the histogram.
- Slot 3
stakind contains the type of statistics which is STATISTIC_KIND_TIME_BOUNDS_HISTOGRAM.staop contains the "<" operator of the time dimension.stavalues stores the histogram of periods for the time dimension.numvalues contains the number of buckets in the histogram.
- Slot 4
stakind contains the type of statistics which is STATISTIC_KIND_TIME_LENGTH_HISTOGRAM.staop contains the "<" operator of the time dimension.stavalues stores the length of the histogram of periods for the time dimension.numvalues contains the number of buckets in the histogram.
In the case of temporal types having a Period as bounding box, that is, tbool and ttext, no statistics are collected for the value dimension and the statistics for the temporal part are stored in slots 1 and 2.
