From: Mike Barry <michael.barry@gmo.com>
Date: Wed, 26 Oct 2022 17:40:32 +0000 (-0400)
Subject: use only object_id() function for temp tables
X-Git-Tag: rel_2_0_0b3~19^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=59f2d0c96152128d8e02e43dcda045593153c86e;p=thirdparty%2Fsqlalchemy%2Fsqlalchemy.git

use only object_id() function for temp tables

Fixed issue with :meth:`.Inspector.has_table` when used against a temporary
table for the SQL Server dialect would fail an invalid object name error on
some Azure variants, due to an unnecessary information schema query that is
not supported on those server versions. Pull request courtesy Mike Barry.

the patch also fills out test support for has_table()
against temp tables, temp views, adding to the has_table() support just
added for views in #8700.

Fixes: #8714
Closes: #8716
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/8716
Pull-request-sha: e2ac7a52e2b09a349a703ba1e1a2911f4d3c0912

Change-Id: Ia73e4e9e977a2d6b7e100abd2f81a8c8777dc9bb
---

diff --git a/doc/build/changelog/unreleased_14/8700.rst b/doc/build/changelog/unreleased_14/8700.rst
index 9e969c3e23..205f251ef4 100644
--- a/doc/build/changelog/unreleased_14/8700.rst
+++ b/doc/build/changelog/unreleased_14/8700.rst
@@ -2,8 +2,9 @@
     :tags: bug, mssql, reflection
     :tickets: 8700
 
-    Fixed regression which occurred throughout the 1.4 series where the
-    :meth:`.Inspector.has_table` method, which historically reported on views
-    as well, stopped working for SQL Server. The issue is not present in the
-    2.0 series which uses a different reflection architecture. Test support is
-    added to ensure ``has_table()`` remains working per spec re: views.
+    Fixed issue with :meth:`.Inspector.has_table` when used against a view for
+    the SQL Server dialect would erroneously return ``False``, due to a
+    regression in the 1.4 series which removed support for this on SQL Server.
+    The issue is not present in the 2.0 series which uses a different
+    reflection architecture. Test support is added to ensure ``has_table()``
+    remains working per spec re: views.
diff --git a/doc/build/changelog/unreleased_14/8714.rst b/doc/build/changelog/unreleased_14/8714.rst
new file mode 100644
index 0000000000..d75f2570ed
--- /dev/null
+++ b/doc/build/changelog/unreleased_14/8714.rst
@@ -0,0 +1,8 @@
+.. change::
+    :tags: bug, mssql
+    :tickets: 8714
+
+    Fixed issue with :meth:`.Inspector.has_table` when used against a temporary
+    table for the SQL Server dialect would fail an invalid object name error on
+    some Azure variants, due to an unnecessary information schema query that is
+    not supported on those server versions. Pull request courtesy Mike Barry.
diff --git a/lib/sqlalchemy/dialects/mssql/base.py b/lib/sqlalchemy/dialects/mssql/base.py
index fdb0704f6c..5d42d98e35 100644
--- a/lib/sqlalchemy/dialects/mssql/base.py
+++ b/lib/sqlalchemy/dialects/mssql/base.py
@@ -3226,28 +3226,13 @@ class MSDialect(default.DefaultDialect):
         if tablename.startswith("#"):  # temporary table
             # mssql does not support temporary views
             # SQL Error [4103] [S0001]: "#v": Temporary views are not allowed
-            tables = ischema.mssql_temp_table_columns
-
-            s = sql.select(tables.c.table_name).where(
-                tables.c.table_name.like(
-                    self._temp_table_name_like_pattern(tablename)
+            return bool(
+                connection.scalar(
+                    # U filters on user tables only.
+                    text("SELECT object_id(:table_name, 'U')"),
+                    {"table_name": "tempdb.dbo.[{}]".format(tablename)},
                 )
             )
-
-            # #7168: fetch all (not just first match) in case some other #temp
-            #        table with the same name happens to appear first
-            table_names = connection.scalars(s).all()
-            # #6910: verify it's not a temp table from another session
-            for table_name in table_names:
-                if bool(
-                    connection.scalar(
-                        text("SELECT object_id(:table_name)"),
-                        {"table_name": "tempdb.dbo.[{}]".format(table_name)},
-                    )
-                ):
-                    return True
-            else:
-                return False
         else:
             tables = ischema.tables
 
diff --git a/lib/sqlalchemy/testing/requirements.py b/lib/sqlalchemy/testing/requirements.py
index 1d6f1103d7..8ceb2af2f6 100644
--- a/lib/sqlalchemy/testing/requirements.py
+++ b/lib/sqlalchemy/testing/requirements.py
@@ -709,6 +709,11 @@ class SuiteRequirements(Requirements):
         """target dialect supports listing of temporary table names"""
         return exclusions.closed()
 
+    @property
+    def has_temp_table(self):
+        """target dialect supports checking a single temp table name"""
+        return exclusions.closed()
+
     @property
     def temporary_tables(self):
         """target database supports temporary tables"""
diff --git a/lib/sqlalchemy/testing/suite/test_reflection.py b/lib/sqlalchemy/testing/suite/test_reflection.py
index dd7d38c5ac..68d1c13faa 100644
--- a/lib/sqlalchemy/testing/suite/test_reflection.py
+++ b/lib/sqlalchemy/testing/suite/test_reflection.py
@@ -45,7 +45,23 @@ from ...testing import mock
 metadata, users = None, None
 
 
-class HasTableTest(fixtures.TablesTest):
+class OneConnectionTablesTest(fixtures.TablesTest):
+    @classmethod
+    def setup_bind(cls):
+        # TODO: when temp tables are subject to server reset,
+        # this will also have to disable that server reset from
+        # happening
+        if config.requirements.independent_connections.enabled:
+            from sqlalchemy import pool
+
+            return engines.testing_engine(
+                options=dict(poolclass=pool.StaticPool, scope="class"),
+            )
+        else:
+            return config.db
+
+
+class HasTableTest(OneConnectionTablesTest):
     __backend__ = True
 
     @classmethod
@@ -67,6 +83,8 @@ class HasTableTest(fixtures.TablesTest):
 
         if testing.requires.view_reflection:
             cls.define_views(metadata)
+        if testing.requires.has_temp_table.enabled:
+            cls.define_temp_tables(metadata)
 
     @classmethod
     def define_views(cls, metadata):
@@ -87,6 +105,37 @@ class HasTableTest(fixtures.TablesTest):
                 DDL("DROP VIEW %s.vv" % (config.test_schema)),
             )
 
+    @classmethod
+    def temp_table_name(cls):
+        return get_temp_table_name(
+            config, config.db, f"user_tmp_{config.ident}"
+        )
+
+    @classmethod
+    def define_temp_tables(cls, metadata):
+        kw = temp_table_keyword_args(config, config.db)
+        table_name = cls.temp_table_name()
+        user_tmp = Table(
+            table_name,
+            metadata,
+            Column("id", sa.INT, primary_key=True),
+            Column("name", sa.VARCHAR(50)),
+            **kw,
+        )
+        if (
+            testing.requires.view_reflection.enabled
+            and testing.requires.temporary_views.enabled
+        ):
+            event.listen(
+                user_tmp,
+                "after_create",
+                DDL(
+                    "create temporary view user_tmp_v as "
+                    "select * from user_tmp_%s" % config.ident
+                ),
+            )
+            event.listen(user_tmp, "before_drop", DDL("drop view user_tmp_v"))
+
     def test_has_table(self):
         with config.db.begin() as conn:
             is_true(config.db.dialect.has_table(conn, "test_table"))
@@ -130,6 +179,19 @@ class HasTableTest(fixtures.TablesTest):
         insp = inspect(connection)
         is_true(insp.has_table("vv"))
 
+    @testing.requires.has_temp_table
+    def test_has_table_temp_table(self, connection):
+        insp = inspect(connection)
+        temp_table_name = self.temp_table_name()
+        is_true(insp.has_table(temp_table_name))
+
+    @testing.requires.has_temp_table
+    @testing.requires.view_reflection
+    @testing.requires.temporary_views
+    def test_has_table_temp_view(self, connection):
+        insp = inspect(connection)
+        is_true(insp.has_table("user_tmp_v"))
+
     @testing.requires.views
     @testing.requires.schemas
     def test_has_table_view_schema(self, connection):
@@ -393,22 +455,11 @@ def _multi_combination(fn):
     return schema(scope(kind(filter_names(fn))))
 
 
-class ComponentReflectionTest(ComparesTables, fixtures.TablesTest):
+class ComponentReflectionTest(ComparesTables, OneConnectionTablesTest):
     run_inserts = run_deletes = None
 
     __backend__ = True
 
-    @classmethod
-    def setup_bind(cls):
-        if config.requirements.independent_connections.enabled:
-            from sqlalchemy import pool
-
-            return engines.testing_engine(
-                options=dict(poolclass=pool.StaticPool, scope="class"),
-            )
-        else:
-            return config.db
-
     @classmethod
     def define_tables(cls, metadata):
         cls.define_reflected_tables(metadata, None)
diff --git a/test/requirements.py b/test/requirements.py
index 69eda37664..e56c944ffc 100644
--- a/test/requirements.py
+++ b/test/requirements.py
@@ -609,6 +609,18 @@ class DefaultRequirements(SuiteRequirements):
             self._sqlite_file_db
         )
 
+    @property
+    def has_temp_table(self):
+        """target dialect supports checking a single temp table name
+
+        unfortunately this is not the same as temp_table_names
+
+        """
+
+        return only_on(["sqlite", "oracle", "postgresql", "mssql"]) + skip_if(
+            self._sqlite_file_db
+        )
+
     @property
     def temporary_views(self):
         """target database supports temporary views"""