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Display length and bounds histograms in pg_stats

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Values corresponding to STATISTIC_KIND_RANGE_LENGTH_HISTOGRAM and
STATISTIC_KIND_BOUNDS_HISTOGRAM were not exposed to pg_stats when these
slot kinds were introduced in 918eee0c49.

This commit adds the missing fields to pg_stats.

Catversion is bumped.

Discussion: https://postgr.es/m/flat/b67d8b57-9357-7e82-a2e7-f6ce6eaeec67@postgrespro.ru
Author: Egor Rogov, Soumyadeep Chakraborty
Reviewed-by: Tomas Vondra, Justin Pryzby, Jian He
This commit is contained in:
Alexander Korotkov
2023-11-27 01:30:39 +02:00
parent 441c8a3134
commit bc3c8db8ae
4 changed files with 87 additions and 3 deletions
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39
doc/src/sgml/system-views.sgml
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@@ -3799,6 +3799,45 @@ SELECT * FROM pg_locks pl LEFT JOIN pg_prepared_xacts ppx
non-null elements. (Null for scalar types.)
</para></entry>
</row>
<row>
<entry role="catalog_table_entry"><para role="column_definition">
<structfield>range_length_histogram</structfield> <type>anyarray</type>
</para>
<para>
A histogram of the lengths of non-empty and non-null range values of a
range type column. (Null for non-range types.)
</para>
<para>
This histogram is calculated using the <literal>subtype_diff</literal>
range function regardless of whether range bounds are inclusive.
</para></entry>
</row>
<row>
<entry role="catalog_table_entry"><para role="column_definition">
<structfield>range_empty_frac</structfield> <type>float4</type>
</para>
<para>
Fraction of column entries whose values are empty ranges.
(Null for non-range types.)
</para></entry>
</row>
<row>
<entry role="catalog_table_entry"><para role="column_definition">
<structfield>range_bounds_histogram</structfield> <type>anyarray</type>
</para>
<para>
A histogram of lower and upper bounds of non-empty and non-null range
values. (Null for non-range types.)
</para>
<para>
These two histograms are represented as a single array of ranges, whose
lower bounds represent the histogram of lower bounds, and upper bounds
represent the histogram of upper bounds.
</para></entry>
</row>
</tbody>
</tgroup>
</table>