Improve Oracle identifier length detection

Use the connection attribute ``max_identifier_length`` available
in oracledb since version 2.5 when determining the identifier length
in the Oracle dialect.

Fixes: #12032
Change-Id: If16db93e0df25776295bc521706dbad1cc541f4a

diff --git a/doc/build/changelog/unreleased_20/12032.rst b/doc/build/changelog/unreleased_20/12032.rst
new file mode 100644 (file)
index 0000000..5a40732
--- /dev/null
+++ b/doc/build/changelog/unreleased_20/12032.rst
@@ -0,0 +1,7 @@
+.. change::
+    :tags: oracle, usecase
+    :tickets: 12032 
+
+    Use the connection attribute ``max_identifier_length`` available
+    in oracledb since version 2.5 when determining the identifier length
+    in the Oracle dialect.

diff --git a/lib/sqlalchemy/dialects/oracle/base.py b/lib/sqlalchemy/dialects/oracle/base.py
index 473e485a41d58fc0fac42cfc2be06c2f6112b147..9d10691d99774dd4e739785ea14e06c4a484664b 100644 (file)
--- a/lib/sqlalchemy/dialects/oracle/base.py
+++ b/lib/sqlalchemy/dialects/oracle/base.py
@@ -188,12 +188,15 @@ To assist with this change and others, Oracle includes the concept of a
 actual server version in order to assist with migration of Oracle databases,
 and may be configured within the Oracle server itself. This compatibility
 version is retrieved using the query  ``SELECT value FROM v$parameter WHERE
-name = 'compatible';``.   The SQLAlchemy Oracle dialect, when tasked with
-determining the default max identifier length, will attempt to use this query
-upon first connect in order to determine the effective compatibility version of
-the server, which determines what the maximum allowed identifier length is for
-the server.  If the table is not available, the  server version information is
-used instead.
+name = 'compatible';``. 
+The SQLAlchemy Oracle dialect, when tasked with determining the default max
+identifier length, will use the ``max_identifier_length`` attribute available
+in the connection of the oracledb driver since version 2.5. When using an older
+version or cx_oracle SQLAlchemy will instead attempted to use the query
+mentioned above upon first connect in order to determine the effective
+compatibility version of the server, which determines what the maximum allowed
+identifier length is for the server. If the table is not available, the server
+version information is used instead.
 
 As of SQLAlchemy 1.4, the default max identifier length for the Oracle dialect
 is 128 characters.  Upon first connect, the compatibility version is detected

diff --git a/lib/sqlalchemy/dialects/oracle/oracledb.py b/lib/sqlalchemy/dialects/oracle/oracledb.py
index 377310f642533be8c9008f87509a110fdb54ff79..ec6f7c035c2772dc464d6cbc21efb3fcb62fcbc1 100644 (file)
--- a/lib/sqlalchemy/dialects/oracle/oracledb.py
+++ b/lib/sqlalchemy/dialects/oracle/oracledb.py
@@ -217,6 +217,12 @@ class OracleDialect_oracledb(_cx_oracle.OracleDialect_cx_oracle):
             for fi, gti, bq in connection.connection.tpc_recover()
         ]
 
+    def _check_max_identifier_length(self, connection):
+        if self.oracledb_ver >= (2, 5):
+            return connection.connection.max_identifier_length
+        else:
+            super()._check_max_identifier_length(connection)
+
 
 class AsyncAdapt_oracledb_cursor(AsyncAdapt_dbapi_cursor):
     _cursor: AsyncCursor
@@ -247,7 +253,7 @@ class AsyncAdapt_oracledb_cursor(AsyncAdapt_dbapi_cursor):
             self._adapt_connection._handle_exception(error)
 
     async def _execute_async(self, operation, parameters):
-        # override to not use mutex, oracledb already has mutex
+        # override to not use mutex, oracledb already has a mutex
 
         if parameters is None:
             result = await self._cursor.execute(operation)
@@ -263,7 +269,7 @@ class AsyncAdapt_oracledb_cursor(AsyncAdapt_dbapi_cursor):
         operation,
         seq_of_parameters,
     ):
-        # override to not use mutex, oracledb already has mutex
+        # override to not use mutex, oracledb already has a mutex
         return await self._cursor.executemany(operation, seq_of_parameters)
 
 
@@ -315,6 +321,10 @@ class AsyncAdapt_oracledb_connection(AsyncAdapt_dbapi_connection):
     def stmtcachesize(self, value):
         self._connection.stmtcachesize = value
 
+    @property
+    def max_identifier_length(self):
+        return self._connection.max_identifier_length
+
     def cursor(self):
         return AsyncAdapt_oracledb_cursor(self)