[Docs]Improve documentation for histograms

Author: hantangwangd

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

@@ -1029,9 +1029,9 @@ The corresponding session property is :ref:`admin/properties-session:\`\`optimiz
 * **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
+during query optimization. When set to ``false``, this parameter prevents histograms from
+being collected by ``ANALYZE``, and also prevents the existing histograms 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

@@ -46,8 +46,9 @@ The following statistics are available in Presto:
 
 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.
+Hive connector does not currently provide statistics on data size or histograms,
+while the Iceberg connector provides both.
 
-Table statistics can be can be fetched using the :doc:`/sql/show-stats` query.
+Table statistics 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.