Document ALTER TABLE EXECUTE OPTIMIZE for Delta Lake connector

docs/src/main/sphinx/connector/delta-lake.rst

@@ -293,11 +293,52 @@ statements, the connector supports the following features:
 * :doc:`/sql/create-schema`, see also :ref:`delta-lake-create-schema`
 * :doc:`/sql/create-table`, see also :ref:`delta-lake-create-table`
 * :doc:`/sql/create-table-as`
-* :doc:`/sql/drop-schema`
 * :doc:`/sql/drop-table`
+* :doc:`/sql/alter-table`
+* :doc:`/sql/drop-schema`
 * :doc:`/sql/show-create-schema`
 * :doc:`/sql/show-create-table`
 
+.. _delta-lake-alter-table-execute:
+
+ALTER TABLE EXECUTE
+^^^^^^^^^^^^^^^^^^^
+
+The connector supports the following commands for use with
+:ref:`ALTER TABLE EXECUTE <alter-table-execute>`.
+
+optimize
+""""""""
+
+The ``optimize`` command is used for rewriting the content
+of the specified table so that it is merged into fewer but larger files.
+In case that the table is partitioned, the data compaction
+acts separately on each partition selected for optimization.
+This operation improves read performance.
+
+All files with a size below the optional ``file_size_threshold``
+parameter (default value for the threshold is ``100MB``) are
+merged:
+
+.. code-block:: sql
+
+    ALTER TABLE test_table EXECUTE optimize
+
+The following statement merges files in a table that are
+under 10 megabytes in size:
+
+.. code-block:: sql
+
+    ALTER TABLE test_table EXECUTE optimize(file_size_threshold => '10MB')
+
+You can use a ``WHERE`` clause with the columns used to partition the table,
+to filter which partitions are optimized:
+
+.. code-block:: sql
+
+    ALTER TABLE test_partitioned_table EXECUTE optimize
+    WHERE partition_key = 1
+
 .. _delta-lake-special-columns:
 
 Special columns