fix(backend): MLMD pagination on getting executions of DAG

backend/src/v2/metadata/client.go

@@ -700,29 +700,42 @@ func (c *Client) GetExecutionsInDAG(ctx context.Context, dag *DAG, pipeline *Pip
 	// Note, because MLMD does not have index on custom properties right now, we
 	// take a pipeline run context to limit the number of executions the DB needs to
 	// iterate through to find sub-executions.
-	res, err := c.svc.GetExecutionsByContext(ctx, &pb.GetExecutionsByContextRequest{
-		ContextId: pipeline.pipelineRunCtx.Id,
-		Options: &pb.ListOperationOptions{
-			FilterQuery: &parentDAGFilter,
-		},
-	})
-	if err != nil {
-		return nil, err
-	}
-	execs := res.GetExecutions()
-	for _, e := range execs {
-		execution := &Execution{execution: e}
-		taskName := execution.TaskName()
-		if taskName == "" {
-			return nil, fmt.Errorf("empty task name for execution ID: %v", execution.GetID())
+
+	nextPageToken := ""
+	for {
+		res, err := c.svc.GetExecutionsByContext(ctx, &pb.GetExecutionsByContextRequest{
+			ContextId: pipeline.pipelineRunCtx.Id,
+			Options: &pb.ListOperationOptions{
+				FilterQuery:   &parentDAGFilter,
+				NextPageToken: &nextPageToken,
+			},
+		})
+		if err != nil {
+			return nil, err
+		}
+
+		execs := res.GetExecutions()
+		for _, e := range execs {
+			execution := &Execution{execution: e}
+			taskName := execution.TaskName()
+			if taskName == "" {
+				return nil, fmt.Errorf("empty task name for execution ID: %v", execution.GetID())
+			}
+			existing, ok := executionsMap[taskName]
+			if ok {
+				// TODO(Bobgy): to support retry, we need to handle multiple tasks with the same task name.
+				return nil, fmt.Errorf("two tasks have the same task name %q, id1=%v id2=%v", taskName, existing.GetID(), execution.GetID())
+			}
+			executionsMap[taskName] = execution
 		}
-		existing, ok := executionsMap[taskName]
-		if ok {
-			// TODO(Bobgy): to support retry, we need to handle multiple tasks with the same task name.
-			return nil, fmt.Errorf("two tasks have the same task name %q, id1=%v id2=%v", taskName, existing.GetID(), execution.GetID())
+
+		nextPageToken = res.GetNextPageToken()
+
+		if nextPageToken == "" {
+			break
 		}
-		executionsMap[taskName] = execution
 	}
+
 	return executionsMap, nil
 }