Add reflection for Identity columns

Added support for reflecting "identity" columns, which are now returned
as part of the structure returned by :meth:`_reflection.Inspector.get_columns`.
When reflecting full :class:`_schema.Table` objects, identity columns will
be represented using the :class:`_schema.Identity` construct.

Fixed compilation error on oracle for sequence and identity column
``nominvalue`` and ``nomaxvalue`` options that require no space in them.

Improved test compatibility with oracle 18.

As part of the support for reflecting :class:`_schema.Identity` objects,
the method :meth:`_reflection.Inspector.get_columns` no longer returns
``mssql_identity_start`` and ``mssql_identity_increment`` as part of the
``dialect_options``. Use the information in the ``identity`` key instead.

The mssql dialect will assume that at least MSSQL 2005 is used.
There is no hard exception raised if a previous version is detected,
but operations may fail for older versions.

Fixes: #5527
Fixes: #5324
Change-Id: If039fe637c46b424499e6bac54a2cbc0dc54cb57

1 files changed, 22 insertions, 2 deletions

diff --git a/test/dialect/oracle/test_compiler.py b/test/dialect/oracle/test_compiler.py
index cea2b5141..869cffe44 100644
--- a/test/dialect/oracle/test_compiler.py
+++ b/test/dialect/oracle/test_compiler.py
@@ -28,6 +28,7 @@ from sqlalchemy.dialects.oracle import base as oracle
 from sqlalchemy.dialects.oracle import cx_oracle
 from sqlalchemy.engine import default
 from sqlalchemy.sql import column
+from sqlalchemy.sql import ddl
 from sqlalchemy.sql import quoted_name
 from sqlalchemy.sql import table
 from sqlalchemy.testing import assert_raises_message
@@ -1258,12 +1259,22 @@ class CompileTest(fixtures.TestBase, AssertsCompiledSQL):
         t = Table(
             "t",
             m,
-            Column("y", Integer, Identity(always=True, start=4, increment=7)),
+            Column(
+                "y",
+                Integer,
+                Identity(
+                    always=True,
+                    start=4,
+                    increment=7,
+                    nominvalue=True,
+                    nomaxvalue=True,
+                ),
+            ),
         )
         self.assert_compile(
             schema.CreateTable(t),
             "CREATE TABLE t (y INTEGER GENERATED ALWAYS AS IDENTITY "
-            "(INCREMENT BY 7 START WITH 4))",
+            "(INCREMENT BY 7 START WITH 4 NOMINVALUE NOMAXVALUE))",
         )
 
     def test_column_identity_no_generated(self):
@@ -1310,6 +1321,15 @@ class SequenceTest(fixtures.TestBase, AssertsCompiledSQL):
             == '"Some_Schema"."My_Seq"'
         )
 
+    def test_compile(self):
+        self.assert_compile(
+            ddl.CreateSequence(
+                Sequence("my_seq", nomaxvalue=True, nominvalue=True)
+            ),
+            "CREATE SEQUENCE my_seq START WITH 1 NOMINVALUE NOMAXVALUE",
+            dialect=oracle.OracleDialect(),
+        )
+
 
 class RegexpTest(fixtures.TestBase, testing.AssertsCompiledSQL):
     __dialect__ = "oracle"