ttl: fix TTL will delete unexpected rows when timezone changed (#41044)

close #41043

ttl/client/notification.go

@@ -73,7 +73,7 @@ func (c *mockClient) WatchNotification(_ context.Context, typ string) clientv3.W
 	c.Lock()
 	defer c.Unlock()
 
-	ch := make(chan clientv3.WatchResponse, 1)
+	ch := make(chan clientv3.WatchResponse, 8)
 	c.notificationWatchers[typ] = append(c.notificationWatchers[typ], ch)
 	return ch
 }

ttl/session/session.go

@@ -148,21 +148,23 @@ func (s *session) RunInTxn(ctx context.Context, fn func() error, txnMode TxnMode
 // ResetWithGlobalTimeZone resets the session time zone to global time zone
 func (s *session) ResetWithGlobalTimeZone(ctx context.Context) error {
 	sessVar := s.GetSessionVars()
-	globalTZ, err := sessVar.GetGlobalSystemVar(ctx, variable.TimeZone)
-	if err != nil {
-		return err
-	}
+	if sessVar.TimeZone != nil {
+		globalTZ, err := sessVar.GetGlobalSystemVar(ctx, variable.TimeZone)
+		if err != nil {
+			return err
+		}
 
-	tz, err := sessVar.GetSessionOrGlobalSystemVar(ctx, variable.TimeZone)
-	if err != nil {
-		return err
-	}
+		tz, err := sessVar.GetSessionOrGlobalSystemVar(ctx, variable.TimeZone)
+		if err != nil {
+			return err
+		}
 
-	if globalTZ == tz {
-		return nil
+		if globalTZ == tz {
+			return nil
+		}
 	}
 
-	_, err = s.ExecuteSQL(ctx, "SET @@time_zone=@@global.time_zone")
+	_, err := s.ExecuteSQL(ctx, "SET @@time_zone=@@global.time_zone")
 	return err
 }
 

ttl/sqlbuilder/sql.go

@@ -32,8 +32,6 @@ import (
 	"github.com/pkg/errors"
 )
 
-const dateTimeFormat = "2006-01-02 15:04:05.999999"
-
 func writeHex(in io.Writer, d types.Datum) error {
 	_, err := fmt.Fprintf(in, "x'%s'", hex.EncodeToString(d.GetBytes()))
 	return err
@@ -183,9 +181,9 @@ func (b *SQLBuilder) WriteExpireCondition(expire time.Time) error {
 
 	b.writeColNames([]*model.ColumnInfo{b.tbl.TimeColumn}, false)
 	b.restoreCtx.WritePlain(" < ")
-	b.restoreCtx.WritePlain("'")
-	b.restoreCtx.WritePlain(expire.Format(dateTimeFormat))
-	b.restoreCtx.WritePlain("'")
+	b.restoreCtx.WritePlain("FROM_UNIXTIME(")
+	b.restoreCtx.WritePlain(strconv.FormatInt(expire.Unix(), 10))
+	b.restoreCtx.WritePlain(")")
 	b.hasWriteExpireCond = true
 	return nil
 }