bpo-41724: Explain when the conversion is not possible with detect_types enabled (GH-23855)
* Explain when the conversion is not possible with detect_types enabled
diff --git a/Doc/library/sqlite3.rst b/Doc/library/sqlite3.rst
index 13aa8c5..c366487 100644
--- a/Doc/library/sqlite3.rst
+++ b/Doc/library/sqlite3.rst
@@ -198,7 +198,9 @@
*detect_types* defaults to 0 (i. e. off, no type detection), you can set it to
any combination of :const:`PARSE_DECLTYPES` and :const:`PARSE_COLNAMES` to turn
- type detection on.
+ type detection on. Due to SQLite behaviour, types can't be detected for generated
+ fields (for example ``max(data)``), even when *detect_types* parameter is set. In
+ such case, the returned type is :class:`str`.
By default, *check_same_thread* is :const:`True` and only the creating thread may
use the connection. If set :const:`False`, the returned connection may be shared