diff --git a/noxfile.py b/noxfile.py
index 265933acd7..42151a22f9 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -238,7 +238,8 @@ def install_systemtest_dependencies(session, *constraints):
 
 
 @nox.session(python=SYSTEM_TEST_PYTHON_VERSIONS)
-def system(session):
+@nox.parametrize("database_dialect", ["GOOGLE_STANDARD_SQL", "POSTGRESQL"])
+def system(session, database_dialect):
     """Run the system test suite."""
     constraints_path = str(
         CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
@@ -256,6 +257,9 @@ def system(session):
         session.skip(
             "Credentials or emulator host must be set via environment variable"
         )
+    # If POSTGRESQL tests and Emulator, skip the tests
+    if os.environ.get("SPANNER_EMULATOR_HOST") and database_dialect == "POSTGRESQL":
+        session.skip("Postgresql is not supported by Emulator yet.")
 
     # Install pyopenssl for mTLS testing.
     if os.environ.get("GOOGLE_API_USE_CLIENT_CERTIFICATE", "false") == "true":
@@ -277,6 +281,10 @@ def system(session):
             f"--junitxml=system_{session.python}_sponge_log.xml",
             system_test_path,
             *session.posargs,
+            env={
+                "SPANNER_DATABASE_DIALECT": database_dialect,
+                "SKIP_BACKUP_TESTS": "true",
+            },
         )
     if system_test_folder_exists:
         session.run(
@@ -285,6 +293,10 @@ def system(session):
             f"--junitxml=system_{session.python}_sponge_log.xml",
             system_test_folder_path,
             *session.posargs,
+            env={
+                "SPANNER_DATABASE_DIALECT": database_dialect,
+                "SKIP_BACKUP_TESTS": "true",
+            },
         )
 
 
diff --git a/tests/system/_helpers.py b/tests/system/_helpers.py
index 51a6d773c4..fba1f1a5a5 100644
--- a/tests/system/_helpers.py
+++ b/tests/system/_helpers.py
@@ -117,7 +117,7 @@ def scrub_instance_ignore_not_found(to_scrub):
 
 
 def cleanup_old_instances(spanner_client):
-    cutoff = int(time.time()) - 2 * 60 * 60  # two hour ago
+    cutoff = int(time.time()) - 3 * 60 * 60  # three hour ago
     instance_filter = "labels.python-spanner-systests:true"
 
     for instance_pb in spanner_client.list_instances(filter_=instance_filter):
diff --git a/tests/system/conftest.py b/tests/system/conftest.py
index b7004fa274..3d6706b582 100644
--- a/tests/system/conftest.py
+++ b/tests/system/conftest.py
@@ -57,6 +57,14 @@ def not_postgres(database_dialect):
         )
 
 
+@pytest.fixture(scope="session")
+def not_google_standard_sql(database_dialect):
+    if database_dialect == DatabaseDialect.GOOGLE_STANDARD_SQL:
+        pytest.skip(
+            f"{_helpers.DATABASE_DIALECT_ENVVAR} set to GOOGLE_STANDARD_SQL in environment."
+        )
+
+
 @pytest.fixture(scope="session")
 def database_dialect():
     return (
@@ -169,14 +177,27 @@ def shared_instance(
 def shared_database(shared_instance, database_operation_timeout, database_dialect):
     database_name = _helpers.unique_id("test_database")
     pool = spanner_v1.BurstyPool(labels={"testcase": "database_api"})
-    database = shared_instance.database(
-        database_name,
-        ddl_statements=_helpers.DDL_STATEMENTS,
-        pool=pool,
-        database_dialect=database_dialect,
-    )
-    operation = database.create()
-    operation.result(database_operation_timeout)  # raises on failure / timeout.
+    if database_dialect == DatabaseDialect.POSTGRESQL:
+        database = shared_instance.database(
+            database_name,
+            pool=pool,
+            database_dialect=database_dialect,
+        )
+        operation = database.create()
+        operation.result(database_operation_timeout)  # raises on failure / timeout.
+
+        operation = database.update_ddl(ddl_statements=_helpers.DDL_STATEMENTS)
+        operation.result(database_operation_timeout)  # raises on failure / timeout.
+
+    else:
+        database = shared_instance.database(
+            database_name,
+            ddl_statements=_helpers.DDL_STATEMENTS,
+            pool=pool,
+            database_dialect=database_dialect,
+        )
+        operation = database.create()
+        operation.result(database_operation_timeout)  # raises on failure / timeout.
 
     yield database
 
diff --git a/tests/system/test_backup_api.py b/tests/system/test_backup_api.py
index bfcd635e8d..dc80653786 100644
--- a/tests/system/test_backup_api.py
+++ b/tests/system/test_backup_api.py
@@ -14,6 +14,7 @@
 
 import datetime
 import time
+from google.cloud.spanner_admin_database_v1.types.common import DatabaseDialect
 
 import pytest
 
@@ -96,14 +97,27 @@ def database_version_time(shared_database):
 def second_database(shared_instance, database_operation_timeout, database_dialect):
     database_name = _helpers.unique_id("test_database2")
     pool = spanner_v1.BurstyPool(labels={"testcase": "database_api"})
-    database = shared_instance.database(
-        database_name,
-        ddl_statements=_helpers.DDL_STATEMENTS,
-        pool=pool,
-        database_dialect=database_dialect,
-    )
-    operation = database.create()
-    operation.result(database_operation_timeout)  # raises on failure / timeout.
+    if database_dialect == DatabaseDialect.POSTGRESQL:
+        database = shared_instance.database(
+            database_name,
+            pool=pool,
+            database_dialect=database_dialect,
+        )
+        operation = database.create()
+        operation.result(database_operation_timeout)  # raises on failure / timeout.
+
+        operation = database.update_ddl(ddl_statements=_helpers.DDL_STATEMENTS)
+        operation.result(database_operation_timeout)  # raises on failure / timeout.
+
+    else:
+        database = shared_instance.database(
+            database_name,
+            ddl_statements=_helpers.DDL_STATEMENTS,
+            pool=pool,
+            database_dialect=database_dialect,
+        )
+        operation = database.create()
+        operation.result(database_operation_timeout)  # raises on failure / timeout.
 
     yield database
 
diff --git a/tests/system/test_database_api.py b/tests/system/test_database_api.py
index 1d21a77498..e9e6c69287 100644
--- a/tests/system/test_database_api.py
+++ b/tests/system/test_database_api.py
@@ -129,6 +129,7 @@ def test_create_database_pitr_success(
 
 def test_create_database_with_default_leader_success(
     not_emulator,  # Default leader setting not supported by the emulator
+    not_postgres,
     multiregion_instance,
     databases_to_delete,
 ):
@@ -270,6 +271,7 @@ def test_update_ddl_w_pitr_success(
 
 def test_update_ddl_w_default_leader_success(
     not_emulator,
+    not_postgres,
     multiregion_instance,
     databases_to_delete,
 ):
diff --git a/tests/system/test_session_api.py b/tests/system/test_session_api.py
index f211577abd..13c3e246ed 100644
--- a/tests/system/test_session_api.py
+++ b/tests/system/test_session_api.py
@@ -200,13 +200,29 @@
 def sessions_database(shared_instance, database_operation_timeout, database_dialect):
     database_name = _helpers.unique_id("test_sessions", separator="_")
     pool = spanner_v1.BurstyPool(labels={"testcase": "session_api"})
-    sessions_database = shared_instance.database(
-        database_name,
-        ddl_statements=_helpers.DDL_STATEMENTS,
-        pool=pool,
-    )
-    operation = sessions_database.create()
-    operation.result(database_operation_timeout)  # raises on failure / timeout.
+
+    if database_dialect == DatabaseDialect.POSTGRESQL:
+        sessions_database = shared_instance.database(
+            database_name,
+            pool=pool,
+            database_dialect=database_dialect,
+        )
+
+        operation = sessions_database.create()
+        operation.result(database_operation_timeout)
+
+        operation = sessions_database.update_ddl(ddl_statements=_helpers.DDL_STATEMENTS)
+        operation.result(database_operation_timeout)
+
+    else:
+        sessions_database = shared_instance.database(
+            database_name,
+            ddl_statements=_helpers.DDL_STATEMENTS,
+            pool=pool,
+        )
+
+        operation = sessions_database.create()
+        operation.result(database_operation_timeout)
 
     _helpers.retry_has_all_dll(sessions_database.reload)()
     # Some tests expect there to be a session present in the pool.
@@ -1322,16 +1338,32 @@ def test_read_w_index(
     # Create an alternate dataase w/ index.
     extra_ddl = ["CREATE INDEX contacts_by_last_name ON contacts(last_name)"]
     pool = spanner_v1.BurstyPool(labels={"testcase": "read_w_index"})
-    temp_db = shared_instance.database(
-        _helpers.unique_id("test_read", separator="_"),
-        ddl_statements=_helpers.DDL_STATEMENTS + extra_ddl,
-        pool=pool,
-        database_dialect=database_dialect,
-    )
-    operation = temp_db.create()
-    databases_to_delete.append(temp_db)
-    operation.result(database_operation_timeout)  # raises on failure / timeout.
 
+    if database_dialect == DatabaseDialect.POSTGRESQL:
+        temp_db = shared_instance.database(
+            _helpers.unique_id("test_read", separator="_"),
+            pool=pool,
+            database_dialect=database_dialect,
+        )
+        operation = temp_db.create()
+        operation.result(database_operation_timeout)
+
+        operation = temp_db.update_ddl(
+            ddl_statements=_helpers.DDL_STATEMENTS + extra_ddl,
+        )
+        operation.result(database_operation_timeout)
+
+    else:
+        temp_db = shared_instance.database(
+            _helpers.unique_id("test_read", separator="_"),
+            ddl_statements=_helpers.DDL_STATEMENTS + extra_ddl,
+            pool=pool,
+            database_dialect=database_dialect,
+        )
+        operation = temp_db.create()
+        operation.result(database_operation_timeout)  # raises on failure / timeout.
+
+    databases_to_delete.append(temp_db)
     committed = _set_up_table(temp_db, row_count)
 
     with temp_db.snapshot(read_timestamp=committed) as snapshot:
@@ -2040,7 +2072,7 @@ def test_execute_sql_w_date_bindings(sessions_database, not_postgres, database_d
 
 
 def test_execute_sql_w_numeric_bindings(
-    not_emulator, not_postgres, sessions_database, database_dialect
+    not_emulator, sessions_database, database_dialect
 ):
     if database_dialect == DatabaseDialect.POSTGRESQL:
         _bind_test_helper(
@@ -2060,7 +2092,9 @@ def test_execute_sql_w_numeric_bindings(
         )
 
 
-def test_execute_sql_w_json_bindings(not_emulator, sessions_database, database_dialect):
+def test_execute_sql_w_json_bindings(
+    not_emulator, not_postgres, sessions_database, database_dialect
+):
     _bind_test_helper(
         sessions_database,
         database_dialect,