Fixed #13245: Explained Oracle's behavior w.r.t db_table

and how to prevent table-name truncation

Thanks russellm & timo for discussion, and timo for review.

docs/ref/databases.txt

@@ -758,6 +758,22 @@ Naming issues
 Oracle imposes a name length limit of 30 characters. To accommodate this, the
 backend truncates database identifiers to fit, replacing the final four
 characters of the truncated name with a repeatable MD5 hash value.
+Additionally, the backend turns database identifiers to all-uppercase.
+
+To prevent these transformations (this is usually required only when dealing
+with legacy databases or accessing tables which belong to other users), use
+a quoted name as the value for ``db_table``::
+
+    class LegacyModel(models.Model):
+        class Meta:
+       	    db_table = '"name_left_in_lowercase"'
+
+    class ForeignModel(models.Model):
+        class Meta:
+       	    db_table = '"OTHER_USER"."NAME_ONLY_SEEMS_OVER_30"'
+
+Quoted names can also be used with Django's other supported database 
+backends; except for Oracle, however, the quotes have no effect.
 
 When running ``migrate``, an ``ORA-06552`` error may be encountered if
 certain Oracle keywords are used as the name of a model field or the

docs/ref/models/options.txt

@@ -72,6 +72,18 @@ Django quotes column and table names behind the scenes.
     the table name via ``db_table``, particularly if you are using the MySQL
     backend. See the :ref:`MySQL notes <mysql-notes>` for more details.
 
+.. admonition:: Table name quoting for Oracle
+
+   In order to to meet the 30-char limitation Oracle has on table names,
+   and match the usual conventions for Oracle databases, Django may shorten
+   table names and turn them all-uppercase. To prevent such transformations,
+   use a quoted name as the value for ``db_table``::
+
+       db_table = '"name_left_in_lowercase"'
+
+   Such quoted names can also be used with Django's other supported database 
+   backends; except for Oracle, however, the quotes have no effect. See the
+   :ref:`Oracle notes <oracle-notes>` for more details.
 
 ``db_tablespace``
 -----------------