Fix schemadiff semantics handling

The problem here is that we store entries in `.Tables` with their
unescaped names, which is entirely safe to do here.

However, we would use `sqlparser.String` to retrieve them. Now that
normally works for table names, unless a table name is a SQL keyword. In
that case, it turns into the escaped version with backticks and the
whole table can't be found for semantic analysis.

This can happen for example if you name a table `Order`.

Signed-off-by: Dirkjan Bussink <d.bussink@gmail.com>

go/vt/schemadiff/schema_diff_test.go

@@ -415,13 +415,15 @@ func TestSchemaDiff(t *testing.T) {
 			instantCapability: InstantDDLCapabilityIrrelevant,
 		},
 		{
-			name: "add view with over",
+			name: "add view with over and keyword table",
 			toQueries: append(
 				createQueries,
-				"create view v2 as SELECT *, ROW_NUMBER() OVER(PARTITION BY info) AS row_num1, ROW_NUMBER() OVER(PARTITION BY info ORDER BY id) AS row_num2 FROM t1;\n",
+				"create table `order` (id int primary key, info int not null);",
+				"create view v2 as SELECT *, ROW_NUMBER() OVER(PARTITION BY info) AS row_num1, ROW_NUMBER() OVER(PARTITION BY info ORDER BY id) AS row_num2 FROM `order`;",
 			),
-			expectDiffs:       1,
-			entityOrder:       []string{"v2"},
+			expectDiffs:       2,
+			expectDeps:        1,
+			entityOrder:       []string{"order", "v2"},
 			instantCapability: InstantDDLCapabilityIrrelevant,
 		},
 		{

go/vt/schemadiff/schema_test.go

@@ -125,6 +125,15 @@ func TestNewSchemaFromQueriesUnresolved(t *testing.T) {
 	assert.Equal(t, "CREATE VIEW `v7` AS SELECT * FROM `v8`, `t2`", v.Create().CanonicalStatementString())
 }
 
+func TestNewSchemaFromQueriesWithSQLKeyword(t *testing.T) {
+	queries := []string{
+		"create table `order` (id int primary key, info int not null)",
+		"create view v2 as SELECT *, ROW_NUMBER() OVER(PARTITION BY info) AS row_num1, ROW_NUMBER() OVER(PARTITION BY info ORDER BY id) AS row_num2 FROM `order`;",
+	}
+	_, err := NewSchemaFromQueries(NewTestEnv(), queries)
+	assert.NoError(t, err)
+}
+
 func TestNewSchemaFromQueriesUnresolvedAlias(t *testing.T) {
 	// v8 does not exist
 	queries := append(schemaTestCreateQueries,

go/vt/schemadiff/semantics.go

@@ -51,7 +51,7 @@ func newDeclarativeSchemaInformation(env *Environment) *declarativeSchemaInforma
 
 // FindTableOrVindex implements the SchemaInformation interface
 func (si *declarativeSchemaInformation) FindTableOrVindex(tablename sqlparser.TableName) (*vindexes.Table, vindexes.Vindex, string, topodatapb.TabletType, key.Destination, error) {
-	table := si.Tables[sqlparser.String(tablename)]
+	table := si.Tables[tablename.Name.String()]
 	return table, nil, "", 0, nil, nil
 }