Add histogram statistic documentation

presto-docs/src/main/sphinx/admin/properties.rst

@@ -863,6 +863,18 @@ on a per-query basis using the ``treat-low-confidence-zero-estimation-as-unknown
 Enable retry for failed queries who can potentially be helped by HBO. This can also be specified
 on a per-query basis using the ``retry-query-with-history-based-optimization`` session property.
 
+``optimizer.use-histograms``
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+* **Type:** ``boolean``
+* **Default Value:** ``false``
+
+Enables the optimizer to use histograms when available to perform cost estimate calculations
+during query optimization. When set to ``false``, this parameter does not prevent histograms
+from being collected by ``ANALYZE``, but prevents them from being used during query
+optimization. This behavior can be controlled on a per-query basis using the
+``optimizer_use_histograms`` session property.
+
 Planner Properties
 ------------------
 

presto-docs/src/main/sphinx/optimizer/statistics.rst

@@ -6,8 +6,9 @@ Presto supports statistics based optimizations for queries. For a query to take
 advantage of these optimizations, Presto must have statistical information for
 the tables in that query.
 
-Table statistics are provided to the query planner by connectors.  Currently, the
-only connector that supports statistics is the :doc:`/connector/hive`.
+Table statistics are provided to the query planner by connectors. Implementing
+support for table statistics is optional. The decision is left to the authors
+of the connector.
 
 Table Layouts
 -------------
@@ -30,23 +31,23 @@ Available Statistics
 
 The following statistics are available in Presto:
 
- * For a table:
+* For a table:
 
-   * **row count**: the total number of rows in the table layout
+  * **row count**: the total number of rows in the table layout
 
- * For each column in a table:
+* For each column in a table:
 
-   * **data size**: the size of the data that needs to be read
-   * **nulls fraction**: the fraction of null values
-   * **distinct value count**: the number of distinct values
-   * **low value**: the smallest value in the column
-   * **high value**: the largest value in the column
+  * **data size**: the size of the data that needs to be read
+  * **nulls fraction**: the fraction of null values
+  * **distinct value count**: the number of distinct values
+  * **low value**: the smallest value in the column
+  * **high value**: the largest value in the column
+  * **histogram**: A connector-dependent histogram data structure.
 
 The set of statistics available for a particular query depends on the connector
 being used and can also vary by table or even by table layout. For example, the
 Hive connector does not currently provide statistics on data size.
 
-Table statistics can be displayed via the Presto SQL interface using the
-:doc:`/sql/show-stats` command. For the Hive connector, refer to the
-:ref:`Hive connector <hive_analyze>` documentation to learn how to update table
-statistics.
+Table statistics can be can be fetched using the :doc:`/sql/show-stats` query.
+For the Hive connector, refer to the :ref:`Hive connector <hive_analyze>`
+documentation to learn how to update table statistics.

presto-docs/src/main/sphinx/sql/show-stats.rst

@@ -60,3 +60,6 @@ The following table lists the returned columns and what statistics they represen
     - The highest value found in this column
     - ``NULL`` in the table summary row. Available for columns of DATE, integer, floating-point, and fixed-precision
       data types.
+  * - ``histogram``
+    - The histogram for this column
+    - A summary of the underlying histogram is displayed in a human-readable format. ``NULL`` in the table summary row.