Document unique bound parameters for text()

Will backport the feature from part of 36e8fe4 / #4808 to
1.3.

Fixes: #4933
Change-Id: Ide4069ff5cccd5ed83a5f314e5f21e51dfe08b7d

1 files changed, 29 insertions, 0 deletions

diff --git a/lib/sqlalchemy/sql/elements.py b/lib/sqlalchemy/sql/elements.py
index 78c434cff..204530ccd 100644
--- a/lib/sqlalchemy/sql/elements.py
+++ b/lib/sqlalchemy/sql/elements.py
@@ -1667,6 +1667,35 @@ class TextClause(
                 timestamp=datetime.datetime(2012, 10, 8, 15, 12, 5)
             )
 
+        The :meth:`.TextClause.bindparams` method also supports the concept of
+        **unique** bound parameters.  These are parameters that are
+        "uniquified" on name at statement compilation time, so that  multiple
+        :func:`.text` constructs may be combined together without the names
+        conflicting.  To use this feature, specify the
+        :paramref:`.BindParameter.unique` flag on each :func:`.bindparam`
+        object::
+
+            stmt1 = text("select id from table where name=:name").bindparams(
+                bindparam("name", value='name1', unique=True)
+            )
+            stmt2 = text("select id from table where name=:name").bindparams(
+                bindparam("name", value='name2', unique=True)
+            )
+
+            union = union_all(
+                stmt1.columns(column("id")),
+                stmt2.columns(column("id"))
+            )
+
+        The above statement will render as::
+
+            select id from table where name=:name_1
+            UNION ALL select id from table where name=:name_2
+
+        .. versionadded:: 1.3.11  Added support for the
+           :paramref:`.BindParameter.unique` flag to work with :func:`.text`
+           constructs.
+
         """
         self._bindparams = new_params = self._bindparams.copy()