[GitHub] [cassandra] fabioueno commented on a change in pull request #745: [CASSANDRA-16117] Improve docs about frozen types and invert UDT/Tuple order

[GitBox <gi...@apache.org>]

fabioueno commented on a change in pull request #745:
URL: https://github.com/apache/cassandra/pull/745#discussion_r498919695



##########
File path: doc/source/cql/types.rst
##########
@@ -400,20 +398,46 @@ Further, lists support:
 
 Lastly, as for :ref:`maps <maps>`, TTLs when used only apply to the newly inserted values.
 
+.. _tuples:
+
+Tuples
+^^^^^^
+
+CQL also support tuples and tuple types (where the elements can be of different types). Tuple types and tuple literals
+are defined by:
+
+.. productionlist::
+   tuple_type: TUPLE '<' `cql_type` ( ',' `cql_type` )* '>'
+   tuple_literal: '(' `term` ( ',' `term` )* ')'
+
+and can be used thusly::
+
+    CREATE TABLE durations (
+        event text,
+        duration tuple<int, text>,
+    )
+
+    INSERT INTO durations (event, duration) VALUES ('ev1', (3, 'hours'));
+
+Unlike other "composed" types (collections and UDT), a tuple is always :ref:`frozen <frozen>` (without the need of the
+`frozen` keyword) and it is not possible to update only some elements of a tuple (without updating the whole tuple).
+Also, a tuple literal should always have the same number of value than declared in the type it is a tuple of (some of
+those values can be null but they need to be explicitly declared as so).
+
 .. _udts:
 
 User-Defined Types
 ^^^^^^^^^^^^^^^^^^
 
-CQL support the definition of user-defined types (UDT for short). Such a type can be created, modified and removed using
-the :token:`create_type_statement`, :token:`alter_type_statement` and :token:`drop_type_statement` described below. But
+CQL support the definition of user-defined types (UDT for short), which is basically a tuple on steroids - it's
+literally an extension of the class that represents a tuple. Such a type can be created, modified and removed using the

Review comment:
       Done, just as you suggested, @blerer! :upside_down_face:




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