feat(server): optimize pagination when counting workflows in archive. Fixes:#13948

.features/pending/pagination-when-counting-workflows.md

@@ -0,0 +1,6 @@
+Component: UI
+Issues: 13948
+Description: Optimize pagination performance when counting workflows in archive.
+Author: [Shuangkun Tian](https://github.com/shuangkun)
+
+When querying archived workflows with pagination, the system now uses more efficient methods to check if there are more items available. Instead of performing expensive full table scans, the new implementation uses LIMIT queries to check if there are items beyond the current offset+limit, significantly improving performance for large datasets.

persist/sqldb/null_workflow_archive.go

@@ -31,6 +31,10 @@ func (r *nullWorkflowArchive) CountWorkflows(ctx context.Context, options sutils
 	return 0, nil
 }
 
+func (r *nullWorkflowArchive) HasMoreWorkflows(ctx context.Context, options sutils.ListOptions) (bool, error) {
+	return false, nil
+}
+
 func (r *nullWorkflowArchive) GetWorkflow(ctx context.Context, uid string, namespace string, name string) (*wfv1.Workflow, error) {
 	return nil, fmt.Errorf("getting archived workflows not supported")
 }

persist/sqldb/workflow_archive.go

@@ -72,6 +72,9 @@ type WorkflowArchive interface {
 	// list workflows, with the most recently started workflows at the beginning (i.e. index 0 is the most recent)
 	ListWorkflows(ctx context.Context, options sutils.ListOptions) (wfv1.Workflows, error)
 	CountWorkflows(ctx context.Context, options sutils.ListOptions) (int64, error)
+	// HasMoreWorkflows efficiently checks if there are more workflows beyond the current offset+limit
+	// This is much faster than counting all workflows for pagination purposes
+	HasMoreWorkflows(ctx context.Context, options sutils.ListOptions) (bool, error)
 	GetWorkflow(ctx context.Context, uid string, namespace string, name string) (*wfv1.Workflow, error)
 	GetWorkflowForEstimator(ctx context.Context, namespace string, requirements []labels.Requirement) (*wfv1.Workflow, error)
 	DeleteWorkflow(ctx context.Context, uid string) error
@@ -275,8 +278,47 @@ func (r *workflowArchive) ListWorkflows(ctx context.Context, options sutils.List
 }
 
 func (r *workflowArchive) CountWorkflows(ctx context.Context, options sutils.ListOptions) (int64, error) {
+	if options.Limit > 0 && options.Offset > 0 {
+		return r.countWorkflowsOptimized(options)
+	}
+
 	total := &archivedWorkflowCount{}
 
+	if len(options.LabelRequirements) == 0 {
+		selector := r.session.SQL().
+			Select(db.Raw("count(*) as total")).
+			From(archiveTableName).
+			Where(r.clusterManagedNamespaceAndInstanceID()).
+			And(namespaceEqual(options.Namespace)).
+			And(namePrefixClause(options.NamePrefix)).
+			And(startedAtFromClause(options.MinStartedAt)).
+			And(startedAtToClause(options.MaxStartedAt)).
+			And(createdAfterClause(options.CreatedAfter)).
+			And(finishedBeforeClause(options.FinishedBefore))
+
+		if options.Name != "" {
+			nameFilter := options.NameFilter
+			if nameFilter == "" {
+				nameFilter = "Exact"
+			}
+			if nameFilter == "Exact" {
+				selector = selector.And(nameEqual(options.Name))
+			}
+			if nameFilter == "Contains" {
+				selector = selector.And(nameContainsClause(options.Name))
+			}
+			if nameFilter == "Prefix" {
+				selector = selector.And(namePrefixClause(options.Name))
+			}
+		}
+
+		err := selector.One(total)
+		if err != nil {
+			return 0, err
+		}
+		return int64(total.Total), nil
+	}
+
 	selector := r.session.SQL().
 		Select(db.Raw("count(*) as total")).
 		From(archiveTableName).
@@ -294,6 +336,107 @@ func (r *workflowArchive) CountWorkflows(ctx context.Context, options sutils.Lis
 	return int64(total.Total), nil
 }
 
+func (r *workflowArchive) countWorkflowsOptimized(options sutils.ListOptions) (int64, error) {
+	sampleSelector := r.session.SQL().
+		Select(db.Raw("count(*) as total")).
+		From(archiveTableName).
+		Where(r.clusterManagedNamespaceAndInstanceID()).
+		And(namespaceEqual(options.Namespace)).
+		And(namePrefixClause(options.NamePrefix)).
+		And(startedAtFromClause(options.MinStartedAt)).
+		And(startedAtToClause(options.MaxStartedAt)).
+		And(createdAfterClause(options.CreatedAfter)).
+		And(finishedBeforeClause(options.FinishedBefore))
+
+	if options.Name != "" {
+		nameFilter := options.NameFilter
+		if nameFilter == "" {
+			nameFilter = "Exact"
+		}
+		if nameFilter == "Exact" {
+			sampleSelector = sampleSelector.And(nameEqual(options.Name))
+		}
+		if nameFilter == "Contains" {
+			sampleSelector = sampleSelector.And(nameContainsClause(options.Name))
+		}
+		if nameFilter == "Prefix" {
+			sampleSelector = sampleSelector.And(namePrefixClause(options.Name))
+		}
+	}
+
+	if options.Offset < 1000 {
+		total := &archivedWorkflowCount{}
+		err := sampleSelector.One(total)
+		if err != nil {
+			return 0, err
+		}
+		return int64(total.Total), nil
+	}
+
+	sampleSize := 1000
+	sampleSelector = sampleSelector.Limit(sampleSize)
+
+	sampleTotal := &archivedWorkflowCount{}
+	err := sampleSelector.One(sampleTotal)
+	if err != nil {
+		return 0, err
+	}
+
+	if int64(sampleTotal.Total) < int64(sampleSize) {
+		return int64(sampleTotal.Total), nil
+	}
+
+	estimatedTotal := int64(options.Offset) + int64(sampleTotal.Total) + int64(options.Limit)
+	return estimatedTotal, nil
+}
+
+func (r *workflowArchive) HasMoreWorkflows(ctx context.Context, options sutils.ListOptions) (bool, error) {
+	selector := r.session.SQL().
+		Select("uid").
+		From(archiveTableName).
+		Where(r.clusterManagedNamespaceAndInstanceID()).
+		And(namespaceEqual(options.Namespace)).
+		And(namePrefixClause(options.NamePrefix)).
+		And(startedAtFromClause(options.MinStartedAt)).
+		And(startedAtToClause(options.MaxStartedAt)).
+		And(createdAfterClause(options.CreatedAfter)).
+		And(finishedBeforeClause(options.FinishedBefore))
+
+	if options.Name != "" {
+		nameFilter := options.NameFilter
+		if nameFilter == "" {
+			nameFilter = "Exact"
+		}
+		if nameFilter == "Exact" {
+			selector = selector.And(nameEqual(options.Name))
+		}
+		if nameFilter == "Contains" {
+			selector = selector.And(nameContainsClause(options.Name))
+		}
+		if nameFilter == "Prefix" {
+			selector = selector.And(namePrefixClause(options.Name))
+		}
+	}
+
+	if len(options.LabelRequirements) > 0 {
+		var err error
+		selector, err = BuildArchivedWorkflowSelector(selector, archiveTableName, archiveLabelsTableName, r.dbType, options, false)
+		if err != nil {
+			return false, err
+		}
+	}
+
+	selector = selector.Limit(1).Offset(options.Offset + options.Limit)
+
+	var result []struct{ UID string }
+	err := selector.All(&result)
+	if err != nil {
+		return false, err
+	}
+
+	return len(result) > 0, nil
+}
+
 func (r *workflowArchive) clusterManagedNamespaceAndInstanceID() *db.AndExpr {
 	return db.And(
 		db.Cond{"clustername": r.clusterName},

server/workflow/workflow_server.go

@@ -201,11 +201,22 @@ func (s *workflowServer) ListWorkflows(ctx context.Context, req *workflowpkg.Wor
 	if err != nil {
 		return nil, sutils.ToStatusError(err, codes.Internal)
 	}
-	archivedCount, err := s.wfArchive.CountWorkflows(ctx, options)
-	if err != nil {
-		return nil, sutils.ToStatusError(err, codes.Internal)
+
+	// Only calculate archivedCount when it's actually needed
+	// This avoids expensive COUNT queries when not necessary
+	var archivedCount int64
+	var totalCount int64
+	if options.ShowRemainingItemCount {
+		archivedCount, err = s.wfArchive.CountWorkflows(ctx, options)
+		if err != nil {
+			return nil, sutils.ToStatusError(err, codes.Internal)
+		}
+		totalCount = liveWfCount + archivedCount
+	} else {
+		// For pagination without remaining count, we can use a more efficient approach
+		// Just check if there are more items beyond the current page
+		totalCount = liveWfCount // Start with live count, will be updated if needed
 	}
-	totalCount := liveWfCount + archivedCount
 
 	// first fetch live workflows
 	liveWfList := &wfv1.WorkflowList{}
@@ -236,16 +247,31 @@ func (s *workflowServer) ListWorkflows(ctx context.Context, req *workflowpkg.Wor
 	if s.wfReflector != nil {
 		meta.ResourceVersion = s.wfReflector.LastSyncResourceVersion()
 	}
-	remainCount := totalCount - int64(options.Offset) - int64(len(wfs))
-	if remainCount < 0 {
-		remainCount = 0
+	var remainCount int64
+	if options.ShowRemainingItemCount {
+		// Calculate exact remaining count when requested
+		remainCount = totalCount - int64(options.Offset) - int64(len(wfs))
+		if remainCount < 0 {
+			remainCount = 0
+		}
+		meta.RemainingItemCount = &remainCount
+	} else {
+		// For pagination without remaining count, use the efficient HasMoreWorkflows method
+		// This avoids expensive COUNT queries
+		hasMore, err := s.wfArchive.HasMoreWorkflows(ctx, options)
+		if err != nil {
+			return nil, sutils.ToStatusError(err, codes.Internal)
+		}
+		if hasMore {
+			remainCount = 1 // There are more items
+		} else {
+			remainCount = 0 // No more items
+		}
 	}
+
 	if remainCount > 0 {
 		meta.Continue = fmt.Sprintf("%v", options.Offset+len(wfs))
 	}
-	if options.ShowRemainingItemCount {
-		meta.RemainingItemCount = &remainCount
-	}
 
 	cleaner := fields.NewCleaner(req.Fields)
 	logger := logging.RequireLoggerFromContext(ctx)

server/workflow/workflow_server_test.go

@@ -617,8 +617,10 @@ func getWorkflowServer(t *testing.T) (workflowpkg.WorkflowServiceServer, context
 	}
 	archivedRepo.On("CountWorkflows", mock.Anything, sutils.ListOptions{Namespace: "workflows", LabelRequirements: r}).Return(int64(2), nil)
 	archivedRepo.On("ListWorkflows", mock.Anything, sutils.ListOptions{Namespace: "workflows", Limit: -2, LabelRequirements: r}).Return(v1alpha1.Workflows{wfObj2, failedWfObj}, nil)
+	archivedRepo.On("HasMoreWorkflows", mock.Anything, sutils.ListOptions{Namespace: "workflows", LabelRequirements: r}).Return(false, nil)
 	archivedRepo.On("CountWorkflows", mock.Anything, sutils.ListOptions{Namespace: "test", LabelRequirements: r}).Return(int64(1), nil)
 	archivedRepo.On("ListWorkflows", mock.Anything, sutils.ListOptions{Namespace: "test", Limit: -1, LabelRequirements: r}).Return(v1alpha1.Workflows{wfObj4}, nil)
+	archivedRepo.On("HasMoreWorkflows", mock.Anything, sutils.ListOptions{Namespace: "test", LabelRequirements: r}).Return(false, nil)
 
 	kubeClientSet := fake.NewSimpleClientset()
 	kubeClientSet.PrependReactor("create", "selfsubjectaccessreviews", func(action ktesting.Action) (handled bool, ret runtime.Object, err error) {