More testing.

src/relstorage/adapters/mysql/drivers/__init__.py

@@ -99,12 +99,12 @@ def visit_upsert_before_select(self, select):
 
         ver_det = select.context.version_detector
         if ver_det.requires_values_upsert_alias(None):
-            self.emit('SELECT * FROM (')
+            self.emit_w_padding_space('SELECT * FROM (')
 
     def visit_upsert_after_select(self, select):
         ver_det = select.context.version_detector
         if ver_det.requires_values_upsert_alias(None):
-            self.emit(') AS excluded')
+            self.emit_w_padding_space(') AS excluded')
 
 
 class MySQLDialect(DefaultDialect):

src/relstorage/adapters/mysql/tests/test_dialect.py

@@ -24,6 +24,7 @@
 class TestMySQLDialect(test_sql.TestUpsert):
     keep_history = False
     dialect = MySQLDialect()
+    REQUIRES_UPSERT = False
 
     insert_or_replace = (
         'INSERT INTO object_state(zoid, state, tid, state_size) '
@@ -48,3 +49,43 @@ class TestMySQLDialect(test_sql.TestUpsert):
         'ON DUPLICATE KEY UPDATE state = VALUES(state), '
         'tid = VALUES(tid), state_size = VALUES(state_size)'
     )
+
+    def get_bind_context(self):
+        requires_upsert = self.REQUIRES_UPSERT
+        class Context:
+            dialect = MySQLDialect()
+            keep_history = False
+            @property
+            def version_detector(self):
+                return self
+            def requires_values_upsert_alias(self, _cursor):
+                return requires_upsert
+        return Context()
+
+class TestMySQLDialect8019(TestMySQLDialect):
+    REQUIRES_UPSERT =  True
+
+    insert_or_replace = (
+        'INSERT INTO object_state(zoid, state, tid, state_size) '
+        'VALUES (%s, %s, %s, %s) AS excluded '
+        'ON DUPLICATE KEY UPDATE '
+        'state = excluded.state, tid = excluded.tid, '
+        'state_size = excluded.state_size'
+    )
+
+    insert_or_replace_subquery = (
+        'INSERT INTO object_state(zoid, tid, state, state_size) '
+        'SELECT * FROM ( SELECT zoid, %s, state, COALESCE(LENGTH(state), 0) FROM temp_store '
+        'ORDER BY zoid ) AS excluded '
+        'ON DUPLICATE KEY UPDATE '
+        'state = excluded.state, tid = excluded.tid, '
+        'state_size = excluded.state_size'
+    )
+
+    upsert_unconstrained_subquery = (
+        'INSERT INTO object_state(zoid, tid, state, state_size) '
+        'SELECT * FROM ( SELECT zoid, %s, state, COALESCE(LENGTH(state), 0) FROM temp_store ) '
+        'AS excluded '
+        'ON DUPLICATE KEY UPDATE state = excluded.state, '
+        'tid = excluded.tid, state_size = excluded.state_size'
+    )

src/relstorage/adapters/sql/dialect.py

@@ -507,6 +507,8 @@ def visit_upsert_before_select(self, select): # pylint:disable=unused-argument
 class _DefaultContext(object):
     keep_history = True
 
+class NoDialectFoundError(TypeError):
+    "Raised when we cannot find a dialect."
 
 class DialectAware(object):
     context = _DefaultContext()
@@ -537,7 +539,10 @@ def _find_dialect(self, context):
             else:
                 return dialect.bind(context)
         __traceback_info__ = getattr(context, '__dict__', ()) # vars() doesn't work on e.g., None
-        raise TypeError("Unable to bind to %s; no dialect found" % (context,))
+        raise NoDialectFoundError("Unable to bind %s to %s; no dialect found" % (
+            type(self),
+            context,
+        ))
 
     def bind(self, context, dialect=None):
         assert self.context is DialectAware.context, "already bound"

src/relstorage/adapters/sql/insert.py

@@ -7,6 +7,8 @@
 from __future__ import division
 from __future__ import print_function
 
+import logging
+
 from zope.interface import implementer
 
 from .query import Query
@@ -23,10 +25,13 @@
 from .expressions import Expression
 from .expressions import ParamMixin
 from .dialect import DialectAware
+from .dialect import NoDialectFoundError
 
 # pylint objects to __compile_visit.*__
 # pylint:disable=bad-dunder-name
 
+logger = logging.getLogger(__name__)
+
 class _ValuesPlaceholderList(ColumnList):
     pass
 
@@ -86,7 +91,11 @@ def __compile_visit__(self, compiler):
             self._visit_select(compiler)
         else:
             values = _InsertValuesClause(self.column_list)
-            values = values.bind(self.context)
+            try:
+                values = values.bind(self.context)
+            except NoDialectFoundError:
+                # Should only happen in testing.
+                logger.debug('Unable to find dialect', exc_info=True)
             compiler.visit(values)
         compiler.emit(self.epilogue)
 
@@ -178,11 +187,16 @@ def do_update(self, *columns):
 
     @property
     def update_clause(self):
-        return Update(EmptyExpression(), _BindableList(
+        update = Update(EmptyExpression(), _BindableList(
             _UpsertAssignmentExpression(col, _ExcludedColumn(col.name))
             for col
             in self.update_columns # pylint:disable=not-an-iterable
-        )).bind(self.context)
+        ))
+        try:
+            return update.bind(self.context)
+        except NoDialectFoundError:
+            # Should only happen in testing
+            return update
 
     def _visit_command(self, compiler):
         compiler.emit_keyword_upsert()

src/relstorage/adapters/sql/tests/test_sql.py

@@ -467,7 +467,7 @@ def test_insert_or_replace(self):
             it.c.state,
             it.c.tid,
             it.c.state_size
-        ).bind(self)
+        ).bind(self.get_bind_context())
 
         self.assertEqual(
             str(stmt),
@@ -509,7 +509,7 @@ def test_insert_or_replace_subquery(self):
             it.c.state,
             it.c.tid,
             it.c.state_size
-        ).bind(self)
+        ).bind(self.get_bind_context())
 
         self.maxDiff = None
         self.assertEqual(
@@ -549,10 +549,13 @@ def test_upsert_unconstrained_subquery(self):
             it.c.state,
             it.c.tid,
             it.c.state_size
-        ).bind(self)
+        ).bind(self.get_bind_context())
 
         self.maxDiff = None
         self.assertEqual(
             str(stmt),
             self.upsert_unconstrained_subquery
         )
+
+    def get_bind_context(self):
+        return self