From 640f0c69f6a3a0f218b4c60aa687286e7d39ea16 Mon Sep 17 00:00:00 2001
From: Rohit Nayak <rohit@planetscale.com>
Date: Thu, 25 Jul 2024 18:40:14 +0530
Subject: [PATCH] Error out if invalid LastPK is passed

Signed-off-by: Rohit Nayak <rohit@planetscale.com>
---
 .../tabletserver/vstreamer/uvstreamer.go      |  8 ++++--
 .../tabletserver/vstreamer/vstreamer_test.go  | 27 +++++++++++++++++++
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/go/vt/vttablet/tabletserver/vstreamer/uvstreamer.go b/go/vt/vttablet/tabletserver/vstreamer/uvstreamer.go
index 2b770c1d4f4..7cb1cc4a579 100644
--- a/go/vt/vttablet/tabletserver/vstreamer/uvstreamer.go
+++ b/go/vt/vttablet/tabletserver/vstreamer/uvstreamer.go
@@ -88,7 +88,7 @@ type uvstreamer struct {
 
 	config *uvstreamerConfig
 
-	vs *vstreamer //last vstreamer created in uvstreamer
+	vs *vstreamer // last vstreamer created in uvstreamer
 }
 
 type uvstreamerConfig struct {
@@ -138,6 +138,10 @@ func (uvs *uvstreamer) buildTablePlan() error {
 	uvs.plans = make(map[string]*tablePlan)
 	tableLastPKs := make(map[string]*binlogdatapb.TableLastPK)
 	for _, tablePK := range uvs.inTablePKs {
+		if tablePK != nil && tablePK.Lastpk != nil && len(tablePK.Lastpk.Fields) == 0 {
+			log.Errorf("lastpk for table %s has no fields defined", tablePK.TableName)
+			return fmt.Errorf("lastpk for table %s has no fields defined", tablePK.TableName)
+		}
 		tableLastPKs[tablePK.TableName] = tablePK
 	}
 	tables := uvs.se.GetSchema()
@@ -313,7 +317,7 @@ func (uvs *uvstreamer) send2(evs []*binlogdatapb.VEvent) error {
 	}
 	behind := time.Now().UnixNano() - uvs.lastTimestampNs
 	uvs.setReplicationLagSeconds(behind / 1e9)
-	//log.Infof("sbm set to %d", uvs.ReplicationLagSeconds)
+	// log.Infof("sbm set to %d", uvs.ReplicationLagSeconds)
 	var evs2 []*binlogdatapb.VEvent
 	if len(uvs.plans) > 0 {
 		evs2 = uvs.filterEvents(evs)
diff --git a/go/vt/vttablet/tabletserver/vstreamer/vstreamer_test.go b/go/vt/vttablet/tabletserver/vstreamer/vstreamer_test.go
index 8d0d182790e..11b53904d6d 100644
--- a/go/vt/vttablet/tabletserver/vstreamer/vstreamer_test.go
+++ b/go/vt/vttablet/tabletserver/vstreamer/vstreamer_test.go
@@ -398,6 +398,33 @@ func TestMissingTables(t *testing.T) {
 	runCases(t, filter, testcases, startPos, nil)
 }
 
+// TestVStreamTableNoPKsWithoutFields confirms that, if a lastpk is passed with no fields defined, it errors out.
+func TestVStreamTableNoPKsWithoutFields(t *testing.T) {
+	ts := &TestSpec{
+		t: t,
+		ddls: []string{
+			"create table t1(id11 int, id12 int, primary key(id11))",
+		},
+	}
+	ts.Init()
+	defer ts.Close()
+	filter := &binlogdatapb.Filter{
+		Rules: []*binlogdatapb.Rule{{
+			Match:  "t1",
+			Filter: "select * from t1",
+		}},
+	}
+	var tablePKs []*binlogdatapb.TableLastPK
+	tablePKs = append(tablePKs, getTablePK("t1", 1))
+	for _, tpk := range tablePKs {
+		tpk.Lastpk.Fields = nil
+	}
+	ctx := context.Background()
+	ch := make(chan []*binlogdatapb.VEvent)
+	err := vstream(ctx, t, "", tablePKs, filter, ch)
+	require.ErrorContains(t, err, "lastpk for table t1 has no fields defined")
+}
+
 func TestVStreamCopySimpleFlow(t *testing.T) {
 	ts := &TestSpec{
 		t: t,