From 1b9c8e95c6bf5f85001ba5535c406693243d3f3f Mon Sep 17 00:00:00 2001
From: Rohit Nayak <rohit@planetscale.com>
Date: Thu, 3 Jun 2021 16:08:42 +0200
Subject: [PATCH] Only reload/update tracked schema in the current schema and
 not for online ddl artifacts

Signed-off-by: Rohit Nayak <rohit@planetscale.com>
---
 go/vt/vttablet/tabletserver/schema/tracker.go | 37 +++++++++++++++++--
 .../tabletserver/schema/tracker_test.go       | 29 +++++++++++++--
 .../tabletserver/vstreamer/vstreamer.go       |  4 +-
 3 files changed, 63 insertions(+), 7 deletions(-)

diff --git a/go/vt/vttablet/tabletserver/schema/tracker.go b/go/vt/vttablet/tabletserver/schema/tracker.go
index 8193fa3dbdd..c76dd5ca6fc 100644
--- a/go/vt/vttablet/tabletserver/schema/tracker.go
+++ b/go/vt/vttablet/tabletserver/schema/tracker.go
@@ -25,6 +25,8 @@ import (
 
 	"google.golang.org/protobuf/proto"
 
+	"vitess.io/vitess/go/vt/schema"
+
 	"vitess.io/vitess/go/mysql"
 
 	"vitess.io/vitess/go/vt/sqlparser"
@@ -136,7 +138,7 @@ func (tr *Tracker) process(ctx context.Context) {
 	defer tr.env.LogError()
 	defer tr.wg.Done()
 	if err := tr.possiblyInsertInitialSchema(ctx); err != nil {
-		log.Errorf("possiblyInsertInitialSchema eror: %v", err)
+		log.Errorf("error inserting initial schema: %v", err)
 		return
 	}
 
@@ -153,10 +155,13 @@ func (tr *Tracker) process(ctx context.Context) {
 				if event.Type == binlogdatapb.VEventType_GTID {
 					gtid = event.Gtid
 				}
-				if event.Type == binlogdatapb.VEventType_DDL {
+				if event.Type == binlogdatapb.VEventType_DDL &&
+					MustReloadSchemaOnDDL(event.Statement, tr.engine.cp.DBName()) {
+
 					if err := tr.schemaUpdated(gtid, event.Statement, event.Timestamp); err != nil {
 						tr.env.Stats().ErrorCounters.Add(vtrpcpb.Code_INTERNAL.String(), 1)
-						log.Errorf("Error updating schema: %s", sqlparser.TruncateForLog(err.Error()))
+						log.Errorf("Error updating schema: %s for ddl %s, gtid %s",
+							sqlparser.TruncateForLog(err.Error()), event.Statement, gtid)
 					}
 				}
 			}
@@ -278,3 +283,29 @@ func encodeString(in string) string {
 	sqltypes.NewVarChar(in).EncodeSQL(buf)
 	return buf.String()
 }
+
+// MustReloadSchemaOnDDL returns true if the ddl is for the db which is part of the workflow and is not an online ddl artifact
+func MustReloadSchemaOnDDL(sql string, dbname string) bool {
+	ast, err := sqlparser.Parse(sql)
+	if err != nil {
+		return false
+	}
+	switch stmt := ast.(type) {
+	case sqlparser.DBDDLStatement:
+		return false
+	case sqlparser.DDLStatement:
+		table := stmt.GetTable()
+		if table.IsEmpty() {
+			return false
+		}
+		if !table.Qualifier.IsEmpty() && table.Qualifier.String() != dbname {
+			return false
+		}
+		tableName := table.Name.String()
+		if schema.IsOnlineDDLTableName(tableName) {
+			return false
+		}
+		return true
+	}
+	return false
+}
diff --git a/go/vt/vttablet/tabletserver/schema/tracker_test.go b/go/vt/vttablet/tabletserver/schema/tracker_test.go
index 8828ece4eb2..39d97dc46a6 100644
--- a/go/vt/vttablet/tabletserver/schema/tracker_test.go
+++ b/go/vt/vttablet/tabletserver/schema/tracker_test.go
@@ -61,7 +61,7 @@ func TestTracker(t *testing.T) {
 			},
 			{
 				Type:      binlogdatapb.VEventType_GTID,
-				Statement: "",
+				Statement: "", // This event should cause an error updating schema since gtid is bad
 			}, {
 				Type:      binlogdatapb.VEventType_DDL,
 				Statement: ddl1,
@@ -84,9 +84,8 @@ func TestTracker(t *testing.T) {
 	<-vs.done
 	cancel()
 	tracker.Close()
-	// Two of those events should have caused an error.
 	final := env.Stats().ErrorCounters.Counts()["INTERNAL"]
-	require.Equal(t, initial+2, final)
+	require.Equal(t, initial+1, final)
 	require.True(t, initialSchemaInserted)
 }
 
@@ -149,3 +148,27 @@ func (f *fakeVstreamer) Stream(ctx context.Context, startPos string, tablePKs []
 	<-ctx.Done()
 	return nil
 }
+
+func TestMustReloadSchemaOnDDL(t *testing.T) {
+	type testcase struct {
+		query  string
+		dbname string
+		want   bool
+	}
+	db1, db2 := "db1", "db2"
+	testcases := []*testcase{
+		{"create table x(i int);", db1, true},
+		{"bad", db2, false},
+		{"create table db2.x(i int);", db2, true},
+		{"create table db1.x(i int);", db2, false},
+		{"create table _vt.x(i int);", db1, false},
+		{"DROP VIEW IF EXISTS `pseudo_gtid`.`_pseudo_gtid_hint__asc:55B364E3:0000000000056EE2:6DD57B85`", db2, false},
+		{"create database db1;", db1, false},
+		{"create table db1._4e5dcf80_354b_11eb_82cd_f875a4d24e90_20201203114014_gho(i int);", db1, false},
+	}
+	for _, tc := range testcases {
+		t.Run("", func(t *testing.T) {
+			require.Equal(t, tc.want, MustReloadSchemaOnDDL(tc.query, tc.dbname))
+		})
+	}
+}
diff --git a/go/vt/vttablet/tabletserver/vstreamer/vstreamer.go b/go/vt/vttablet/tabletserver/vstreamer/vstreamer.go
index 65347a2cca6..a2496711b5c 100644
--- a/go/vt/vttablet/tabletserver/vstreamer/vstreamer.go
+++ b/go/vt/vttablet/tabletserver/vstreamer/vstreamer.go
@@ -463,7 +463,9 @@ func (vs *vstreamer) parseEvent(ev mysql.BinlogEvent) ([]*binlogdatapb.VEvent, e
 					Type: binlogdatapb.VEventType_OTHER,
 				})
 			}
-			vs.se.ReloadAt(context.Background(), vs.pos)
+			if schema.MustReloadSchemaOnDDL(q.SQL, vs.cp.DBName()) {
+				vs.se.ReloadAt(context.Background(), vs.pos)
+			}
 		case sqlparser.StmtSavepoint:
 			mustSend := mustSendStmt(q, vs.cp.DBName())
 			if mustSend {