Fixing a bug in table blacklisting.

If a tablet has blacklisted table rules that don't match
any existing tables, don't blacklist exverything.
In the process, allowing schema changes on databases with views,
as the integration test needs it, and it's a good fix anyway.

go/vt/mysqlctl/schema.go

@@ -218,6 +218,14 @@ func (mysqld *Mysqld) PreflightSchemaChange(dbName string, change string) (*tmut
 			sql += td.Schema + ";\n"
 		}
 	}
+	for _, td := range beforeSchema.TableDefinitions {
+		if td.Type == tmutils.TableView {
+			// Views will have {{.DatabaseName}} in there, replace
+			// it with _vt_preflight
+			s := strings.Replace(td.Schema, "`{{.DatabaseName}}`", "`_vt_preflight`", -1)
+			sql += s + ";\n"
+		}
+	}
 	if err = mysqld.executeMysqlCommands(mysqld.dba.Uname, sql); err != nil {
 		return nil, err
 	}
@@ -249,7 +257,7 @@ func (mysqld *Mysqld) PreflightSchemaChange(dbName string, change string) (*tmut
 // ApplySchemaChange will apply the schema change to the given database.
 func (mysqld *Mysqld) ApplySchemaChange(dbName string, change *tmutils.SchemaChange) (*tmutils.SchemaChangeResult, error) {
 	// check current schema matches
-	beforeSchema, err := mysqld.GetSchema(dbName, nil, nil, false)
+	beforeSchema, err := mysqld.GetSchema(dbName, nil, nil, true)
 	if err != nil {
 		return nil, err
 	}
@@ -296,7 +304,7 @@ func (mysqld *Mysqld) ApplySchemaChange(dbName string, change *tmutils.SchemaCha
 	}
 
 	// get AfterSchema
-	afterSchema, err := mysqld.GetSchema(dbName, nil, nil, false)
+	afterSchema, err := mysqld.GetSchema(dbName, nil, nil, true)
 	if err != nil {
 		return nil, err
 	}

go/vt/tabletmanager/state_change.go

@@ -51,12 +51,18 @@ func (agent *ActionAgent) loadBlacklistRules(tablet *topodatapb.Tablet, blacklis
 		if err != nil {
 			return err
 		}
-		log.Infof("Blacklisting tables %v", strings.Join(tables, ", "))
-		qr := tabletserver.NewQueryRule("enforce blacklisted tables", "blacklisted_table", tabletserver.QRFailRetry)
-		for _, t := range tables {
-			qr.AddTableCond(t)
+
+		// if the wildcards resolve into real tables, blacklist them.
+		// (if there are no tables here, the rule would blacklist
+		// all queries, oops).
+		if len(tables) > 0 {
+			log.Infof("Blacklisting tables %v", strings.Join(tables, ", "))
+			qr := tabletserver.NewQueryRule("enforce blacklisted tables", "blacklisted_table", tabletserver.QRFailRetry)
+			for _, t := range tables {
+				qr.AddTableCond(t)
+			}
+			blacklistRules.Add(qr)
 		}
-		blacklistRules.Add(qr)
 	}
 
 	loadRuleErr := agent.QueryServiceControl.SetQueryRules(blacklistQueryRules, blacklistRules)

test/vertical_split.py

@@ -536,6 +536,24 @@ index by_msg (msg)
     # check the stats are correct
     self._check_stats()
 
+    # now remove the tables on the source shard. The blacklisted tables
+    # in the source shard won't match any table, make sure that works.
+    utils.run_vtctl(['ApplySchema',
+                     '-sql=drop view view1',
+                     'source_keyspace'],
+                    auto_log=True)
+    for t in ['moving1', 'moving2']:
+      utils.run_vtctl(['ApplySchema',
+                       '-sql=drop table %s' % (t),
+                       'source_keyspace'],
+                      auto_log=True)
+    for t in [source_master, source_replica, source_rdonly1, source_rdonly2]:
+      utils.run_vtctl(['ReloadSchema', t.tablet_alias])
+    qr = source_master.execute('select count(1) from staying1')
+    self.assertEqual(len(qr['rows']), 1,
+                     'cannot read staying1: got %s' % str(qr))
+
+    # test SetShardTabletControl
     self._verify_vtctl_set_shard_tablet_control()
 
   def _verify_vtctl_set_shard_tablet_control(self):