perf(nextup): batch the user data reads the next episode selection makes

Next Up walked every series in an unpaginated loop and read user data one
episode at a time, so the Home screen row cost two queries per series once the
cache was gone.

- read the played state of every candidate episode in one query
- read the versions the resume check and the last played date need in one query each
- default PrefetchedUserData on IUserBaseItemComparer so plugin comparers still compile
- cover the bounded query count and the plugin comparer with tests
- share one database across the replica tests

Emby.Server.Implementations/TV/TVSeriesManager.cs

@@ -13,6 +13,7 @@ using MediaBrowser.Controller.Configuration;
 using MediaBrowser.Controller.Dto;
 using MediaBrowser.Controller.Entities;
 using MediaBrowser.Controller.Library;
+using MediaBrowser.Controller.Persistence;
 using MediaBrowser.Controller.TV;
 using MediaBrowser.Model.Querying;
 using Episode = MediaBrowser.Controller.Entities.TV.Episode;
@@ -124,53 +125,100 @@ namespace Emby.Server.Implementations.TV
 
             var batchResult = _libraryManager.GetNextUpEpisodesBatch(query, seriesKeys, includeSpecials, includeRewatching);
 
-            var nextUpList = new List<(DateTime LastWatchedDate, Episode Episode)>();
-
+            var results = new List<NextUpEpisodeBatchResult>(seriesKeys.Count);
             foreach (var seriesKey in seriesKeys)
             {
-                if (!batchResult.TryGetValue(seriesKey, out var result))
+                if (batchResult.TryGetValue(seriesKey, out var result))
                 {
-                    continue;
+                    results.Add(result);
                 }
+            }
 
-                var nextEpisode = DetermineNextEpisode(result, user, includeSpecials, request.EnableResumable, false);
+            // The selection below tests the played state of every episode it considers, so read the whole
+            // series batch in one query rather than one query per series.
+            var selectionCandidates = new List<BaseItem>();
+            foreach (var result in results)
+            {
+                AddCandidate(selectionCandidates, result.NextUp);
+                AddCandidate(selectionCandidates, result.LastWatched);
+                AddCandidate(selectionCandidates, result.NextPlayedForRewatching);
+                AddCandidate(selectionCandidates, result.LastWatchedForRewatching);
 
+                if (result.Specials is not null)
+                {
+                    selectionCandidates.AddRange(result.Specials);
+                }
+            }
+
+            var selectionUserData = _userDataManager.GetUserDataBatch(selectionCandidates, user);
+
+            var candidates = new List<NextUpCandidate>();
+            foreach (var result in results)
+            {
+                var nextEpisode = SelectNextEpisode(result, user, includeSpecials, includePlayed: false, selectionUserData);
                 if (nextEpisode is not null)
                 {
-                    // The last played date and the version that was actually played live on the version item's user data
-                    // The played state propagated to the sibling versions carries no date
-                    var (playedVersion, lastPlayedDate) = GetMostRecentlyPlayedVersion(result.LastWatched, user);
-                    nextEpisode = GetPreferredVersion(nextEpisode, result.LastWatched, playedVersion);
-
-                    DateTime lastWatchedDate = DateTime.MinValue;
-                    if (result.LastWatched is not null)
-                    {
-                        lastWatchedDate = lastPlayedDate ?? DateTime.MinValue.AddDays(1);
-                    }
-
-                    nextUpList.Add((lastWatchedDate, nextEpisode));
+                    candidates.Add(new NextUpCandidate(nextEpisode, result.LastWatched, !request.EnableResumable));
                 }
 
                 if (includeRewatching)
                 {
-                    var nextPlayedEpisode = DetermineNextEpisodeForRewatching(result, user, includeSpecials);
-
+                    var nextPlayedEpisode = SelectNextEpisode(result, user, includeSpecials, includePlayed: true, selectionUserData);
                     if (nextPlayedEpisode is not null)
                     {
-                        var (playedVersion, lastPlayedDate) = GetMostRecentlyPlayedVersion(result.LastWatchedForRewatching, user);
-                        nextPlayedEpisode = GetPreferredVersion(nextPlayedEpisode, result.LastWatchedForRewatching, playedVersion);
-
-                        DateTime rewatchLastWatchedDate = DateTime.MinValue;
-                        if (result.LastWatchedForRewatching is not null)
-                        {
-                            rewatchLastWatchedDate = lastPlayedDate ?? DateTime.MinValue.AddDays(1);
-                        }
-
-                        nextUpList.Add((rewatchLastWatchedDate, nextPlayedEpisode));
+                        // A rewatch suggestion is dropped once it has been resumed, whatever the request asked for.
+                        candidates.Add(new NextUpCandidate(nextPlayedEpisode, result.LastWatchedForRewatching, true));
                     }
                 }
             }
 
+            // The resume progress may live on an alternate version, so read every version in one query.
+            var episodeVersions = new List<BaseItem>();
+            foreach (var candidate in candidates)
+            {
+                if (candidate.DropWhenResumed)
+                {
+                    candidate.EpisodeVersions = candidate.Episode.GetAllVersions();
+                    episodeVersions.AddRange(candidate.EpisodeVersions);
+                }
+            }
+
+            if (episodeVersions.Count > 0)
+            {
+                var resumeUserData = _userDataManager.GetUserDataBatch(episodeVersions, user);
+                candidates.RemoveAll(candidate => candidate.EpisodeVersions
+                    .Any(version => GetUserData(user, version, resumeUserData)?.PlaybackPositionTicks > 0));
+            }
+
+            // The last played date and the version that was actually played live on the version item's user data
+            // The played state propagated to the sibling versions carries no date
+            var lastWatchedVersions = new List<BaseItem>();
+            foreach (var candidate in candidates)
+            {
+                if (candidate.LastWatched is Video lastWatchedVideo)
+                {
+                    candidate.LastWatchedVersions = lastWatchedVideo.GetAllVersions();
+                    lastWatchedVersions.AddRange(candidate.LastWatchedVersions);
+                }
+            }
+
+            var lastWatchedUserData = _userDataManager.GetUserDataBatch(lastWatchedVersions, user);
+
+            var nextUpList = new List<(DateTime LastWatchedDate, Episode Episode)>(candidates.Count);
+            foreach (var candidate in candidates)
+            {
+                var (playedVersion, lastPlayedDate) = GetMostRecentlyPlayedVersion(candidate.LastWatchedVersions, user, lastWatchedUserData);
+                var nextEpisode = GetPreferredVersion(candidate.Episode, candidate.LastWatched, playedVersion);
+
+                DateTime lastWatchedDate = DateTime.MinValue;
+                if (candidate.LastWatched is not null)
+                {
+                    lastWatchedDate = lastPlayedDate ?? DateTime.MinValue.AddDays(1);
+                }
+
+                nextUpList.Add((lastWatchedDate, nextEpisode));
+            }
+
             var sortedEpisodes = nextUpList
                 .OrderByDescending(x => x.LastWatchedDate)
                 .Select(x => (BaseItem)x.Episode);
@@ -178,12 +226,25 @@ namespace Emby.Server.Implementations.TV
             return GetResult(sortedEpisodes, request);
         }
 
-        private Episode? DetermineNextEpisode(
-            MediaBrowser.Controller.Persistence.NextUpEpisodeBatchResult result,
+        private static void AddCandidate(List<BaseItem> candidates, BaseItem? item)
+        {
+            if (item is not null)
+            {
+                candidates.Add(item);
+            }
+        }
+
+        private UserItemData? GetUserData(User user, BaseItem item, IReadOnlyDictionary<Guid, UserItemData> prefetchedUserData)
+            => prefetchedUserData.TryGetValue(item.Id, out var userData)
+                ? userData
+                : _userDataManager.GetUserData(user, item);
+
+        private Episode? SelectNextEpisode(
+            NextUpEpisodeBatchResult result,
             User user,
             bool includeSpecials,
-            bool includeResumable,
-            bool includePlayed)
+            bool includePlayed,
+            IReadOnlyDictionary<Guid, UserItemData> prefetchedUserData)
         {
             var nextEpisode = (includePlayed ? result.NextPlayedForRewatching : result.NextUp) as Episode;
             var lastWatchedEpisode = (includePlayed ? result.LastWatchedForRewatching : result.LastWatched) as Episode;
@@ -217,60 +278,41 @@ namespace Emby.Server.Implementations.TV
 
                     if (!includePlayed)
                     {
-                        sortedEpisodes = sortedEpisodes.Where(episode => _userDataManager.GetUserData(user, episode) is not { Played: true });
+                        sortedEpisodes = sortedEpisodes.Where(episode => GetUserData(user, episode, prefetchedUserData) is not { Played: true });
                     }
 
                     nextEpisode = sortedEpisodes.FirstOrDefault();
                 }
             }
 
-            if (nextEpisode is not null && !includeResumable)
-            {
-                // The resume progress may live on an alternate version
-                foreach (var version in nextEpisode.GetAllVersions())
-                {
-                    if (_userDataManager.GetUserData(user, version)?.PlaybackPositionTicks > 0)
-                    {
-                        return null;
-                    }
-                }
-            }
-
             return nextEpisode;
         }
 
-        private Episode? DetermineNextEpisodeForRewatching(
-            MediaBrowser.Controller.Persistence.NextUpEpisodeBatchResult result,
-            User user,
-            bool includeSpecials)
-        {
-            return DetermineNextEpisode(result, user, includeSpecials, includeResumable: false, includePlayed: true);
-        }
-
         /// <summary>
         /// Gets the version of the last watched episode that was actually played, together with its last played date.
         /// The version that was played carries the most recent LastPlayedDate.
         /// dates.
         /// </summary>
-        /// <param name="lastWatched">The last watched episode (any version).</param>
+        /// <param name="versions">The versions of the last watched episode.</param>
         /// <param name="user">The user.</param>
+        /// <param name="prefetchedUserData">User data read for every version up front.</param>
         /// <returns>The played version and its last played date.</returns>
-        private (Video? PlayedVersion, DateTime? LastPlayedDate) GetMostRecentlyPlayedVersion(BaseItem? lastWatched, User user)
+        private (Video? PlayedVersion, DateTime? LastPlayedDate) GetMostRecentlyPlayedVersion(
+            IReadOnlyList<Video> versions,
+            User user,
+            IReadOnlyDictionary<Guid, UserItemData> prefetchedUserData)
         {
-            if (lastWatched is not Video lastWatchedVideo)
+            if (versions.Count == 0)
             {
                 return (null, null);
             }
 
-            var versions = lastWatchedVideo.GetAllVersions();
-            var userDataByVersion = _userDataManager.GetUserDataBatch(versions, user);
-
             var playedVersion = VersionPlaybackSelector.SelectMostRecentlyPlayed(
                 versions,
-                version => userDataByVersion.GetValueOrDefault(version.Id),
+                version => GetUserData(user, version, prefetchedUserData),
                 data => data.LastPlayedDate.HasValue);
 
-            return (playedVersion, playedVersion is null ? null : userDataByVersion[playedVersion.Id].LastPlayedDate);
+            return (playedVersion, playedVersion is null ? null : GetUserData(user, playedVersion, prefetchedUserData)?.LastPlayedDate);
         }
 
         /// <summary>
@@ -346,5 +388,28 @@ namespace Emby.Server.Implementations.TV
                 totalCount,
                 items.ToArray());
         }
+
+        /// <summary>
+        /// An episode picked for Next Up, together with the versions its user data is read from.
+        /// </summary>
+        private sealed class NextUpCandidate
+        {
+            public NextUpCandidate(Episode episode, BaseItem? lastWatched, bool dropWhenResumed)
+            {
+                Episode = episode;
+                LastWatched = lastWatched;
+                DropWhenResumed = dropWhenResumed;
+            }
+
+            public Episode Episode { get; }
+
+            public BaseItem? LastWatched { get; }
+
+            public bool DropWhenResumed { get; }
+
+            public IReadOnlyList<Video> EpisodeVersions { get; set; } = [];
+
+            public IReadOnlyList<Video> LastWatchedVersions { get; set; } = [];
+        }
     }
 }

MediaBrowser.Controller/Sorting/IUserBaseItemComparer.cs

@@ -33,8 +33,13 @@ namespace MediaBrowser.Controller.Sorting
 
         /// <summary>
         /// Gets or sets user data for the items being sorted, keyed by item id, read once up front.
+        /// A comparer that does not store it reads its user data one item at a time instead.
         /// </summary>
         /// <value>The prefetched user data, or <c>null</c> when none was prefetched.</value>
-        IReadOnlyDictionary<Guid, UserItemData> PrefetchedUserData { get; set; }
+        IReadOnlyDictionary<Guid, UserItemData> PrefetchedUserData
+        {
+            get => null;
+            set { }
+        }
     }
 }

tests/Jellyfin.Server.Implementations.Tests/Library/LibraryManagerSortTests.cs

@@ -7,6 +7,7 @@ using Emby.Naming.Common;
 using Emby.Server.Implementations.Library;
 using Emby.Server.Implementations.Sorting;
 using Jellyfin.Data.Enums;
+using Jellyfin.Database.Implementations.Entities;
 using Jellyfin.Database.Implementations.Enums;
 using MediaBrowser.Controller.Configuration;
 using MediaBrowser.Controller.Entities;
@@ -63,13 +64,49 @@ public class LibraryManagerSortTests
         Assert.Equal(new[] { "Alpha", "Mike", "Zulu" }, sorted.Select(i => i.Name));
     }
 
+    [Fact]
+    public void Sort_ComparerThatIgnoresPrefetchedUserData_StillSortsFromLiveReads()
+    {
+        var alpha = new Audio { Name = "Alpha", SortName = "Alpha", Id = Guid.NewGuid() };
+        var zulu = new Audio { Name = "Zulu", SortName = "Zulu", Id = Guid.NewGuid() };
+        var playCounts = new Dictionary<Guid, int> { [alpha.Id] = 1, [zulu.Id] = 9 };
+
+        var userDataManager = new Mock<IUserDataManager>();
+        userDataManager
+            .Setup(u => u.GetUserData(It.IsAny<User>(), It.IsAny<BaseItem>()))
+            .Returns<User, BaseItem>((_, item) => new UserItemData { Key = item.Id.ToString("N"), PlayCount = playCounts[item.Id] });
+        userDataManager
+            .Setup(u => u.GetUserDataBatch(It.IsAny<IReadOnlyList<BaseItem>>(), It.IsAny<User>()))
+            .Returns(new Dictionary<Guid, UserItemData>());
+
+        var libraryManager = CreateLibraryManager(
+            new IBaseItemComparer[] { new PluginPlayCountComparer() },
+            userDataManager);
+
+        var sorted = libraryManager.Sort(
+            new BaseItem[] { alpha, zulu },
+            new User("sorter", "provider", "provider"),
+            new[] { (ItemSortBy.PlayCount, SortOrder.Descending) }).ToArray();
+
+        Assert.Equal(new[] { "Zulu", "Alpha" }, sorted.Select(i => i.Name));
+        userDataManager.Verify(u => u.GetUserData(It.IsAny<User>(), It.IsAny<BaseItem>()), Times.AtLeastOnce);
+    }
+
     private static Folder MakeFolder(string name, DateTime dateLastMediaAdded)
         => new() { Name = name, Id = Guid.NewGuid(), DateLastMediaAdded = dateLastMediaAdded };
 
-    private static Emby.Server.Implementations.Library.LibraryManager CreateLibraryManager(IReadOnlyCollection<IBaseItemComparer> comparers)
+    private static Emby.Server.Implementations.Library.LibraryManager CreateLibraryManager(
+        IReadOnlyCollection<IBaseItemComparer> comparers,
+        Mock<IUserDataManager>? userDataManager = null)
     {
         var fixture = new Fixture().Customize(new AutoMoqCustomization());
         fixture.Register(() => new NamingOptions());
+
+        if (userDataManager is not null)
+        {
+            fixture.Inject(userDataManager.Object);
+        }
+
         var configMock = fixture.Freeze<Mock<IServerConfigurationManager>>();
         configMock.Setup(c => c.ApplicationPaths.ProgramDataPath).Returns("/data");
         BaseItem.ConfigurationManager ??= configMock.Object;
@@ -86,4 +123,22 @@ public class LibraryManagerSortTests
                 fixture.Create<IEnumerable<ILibraryPostScanTask>>()))
             .Create();
     }
+
+    /// <summary>
+    /// A comparer of the shape a third-party plugin ships: it implements
+    /// <see cref="IUserBaseItemComparer"/> without ever mentioning PrefetchedUserData.
+    /// </summary>
+    public sealed class PluginPlayCountComparer : IUserBaseItemComparer
+    {
+        public User User { get; set; } = null!;
+
+        public IUserManager UserManager { get; set; } = null!;
+
+        public IUserDataManager UserDataManager { get; set; } = null!;
+
+        public ItemSortBy Type => ItemSortBy.PlayCount;
+
+        public int Compare(BaseItem? x, BaseItem? y)
+            => UserDataManager.GetUserData(User, x!)!.PlayCount.CompareTo(UserDataManager.GetUserData(User, y!)!.PlayCount);
+    }
 }

tests/Jellyfin.Server.Implementations.Tests/TV/TVSeriesManagerNextUpTests.cs

@@ -0,0 +1,94 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
+using Emby.Server.Implementations.TV;
+using Jellyfin.Database.Implementations.Entities;
+using MediaBrowser.Controller.Configuration;
+using MediaBrowser.Controller.Dto;
+using MediaBrowser.Controller.Entities;
+using MediaBrowser.Controller.Entities.TV;
+using MediaBrowser.Controller.Library;
+using MediaBrowser.Controller.Persistence;
+using MediaBrowser.Model.Configuration;
+using MediaBrowser.Model.Querying;
+using Moq;
+using Xunit;
+
+namespace Jellyfin.Server.Implementations.Tests.TV;
+
+public class TVSeriesManagerNextUpTests
+{
+    [Theory]
+    [InlineData(1)]
+    [InlineData(25)]
+    [InlineData(200)]
+    public void GetNextUp_ReadsUserDataInABoundedNumberOfQueries(int seriesCount)
+    {
+        var user = new User("next-up", "provider", "provider");
+        var libraryManager = new Mock<ILibraryManager>();
+        var userDataManager = new Mock<IUserDataManager>();
+
+        var seriesKeys = Enumerable.Range(0, seriesCount)
+            .Select(i => i.ToString(CultureInfo.InvariantCulture))
+            .ToList();
+
+        var batch = seriesKeys.ToDictionary(
+            key => key,
+            key => new NextUpEpisodeBatchResult
+            {
+                NextUp = new Episode { Id = Guid.NewGuid(), Name = "Next " + key },
+                LastWatched = new Episode { Id = Guid.NewGuid(), Name = "Watched " + key }
+            });
+
+        libraryManager
+            .Setup(l => l.GetNextUpSeriesKeys(It.IsAny<InternalItemsQuery>(), It.IsAny<IReadOnlyCollection<BaseItem>>(), It.IsAny<DateTime>()))
+            .Returns(seriesKeys);
+        libraryManager
+            .Setup(l => l.GetNextUpEpisodesBatch(It.IsAny<InternalItemsQuery>(), It.IsAny<IReadOnlyList<string>>(), It.IsAny<bool>(), It.IsAny<bool>()))
+            .Returns(batch);
+        libraryManager.Setup(l => l.GetLinkedAlternateVersions(It.IsAny<Video>())).Returns([]);
+        libraryManager.Setup(l => l.GetLocalAlternateVersionIds(It.IsAny<Video>())).Returns([]);
+
+        var batchReads = 0;
+        userDataManager
+            .Setup(u => u.GetUserDataBatch(It.IsAny<IReadOnlyList<BaseItem>>(), It.IsAny<User>()))
+            .Returns<IReadOnlyList<BaseItem>, User>((items, _) =>
+            {
+                batchReads++;
+                return items.DistinctBy(i => i.Id).ToDictionary(
+                    i => i.Id,
+                    i => new UserItemData { Key = i.Id.ToString("N", CultureInfo.InvariantCulture) });
+            });
+
+        var previousLibraryManager = BaseItem.LibraryManager;
+        BaseItem.LibraryManager = libraryManager.Object;
+
+        try
+        {
+            var manager = new TVSeriesManager(userDataManager.Object, libraryManager.Object, CreateConfigurationManager());
+
+            var result = manager.GetNextUp(
+                new NextUpQuery { User = user, EnableTotalRecordCount = true },
+                [],
+                new DtoOptions(false));
+
+            Assert.Equal(seriesCount, result.TotalRecordCount);
+
+            // Selection, the resume check and the last played date: three reads whatever the library holds.
+            Assert.Equal(3, batchReads);
+            userDataManager.Verify(u => u.GetUserData(It.IsAny<User>(), It.IsAny<BaseItem>()), Times.Never);
+        }
+        finally
+        {
+            BaseItem.LibraryManager = previousLibraryManager;
+        }
+    }
+
+    private static IServerConfigurationManager CreateConfigurationManager()
+    {
+        var configurationManager = new Mock<IServerConfigurationManager>();
+        configurationManager.SetupGet(c => c.Configuration).Returns(new ServerConfiguration());
+        return configurationManager.Object;
+    }
+}

tests/Jellyfin.Server.Tests/Library/UserDataManagerReplicaTests.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Globalization;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
@@ -28,22 +29,15 @@ namespace Jellyfin.Server.Tests.Library;
 /// see on its very next read, and a read-modify-write on one must not roll back the other's.
 /// </summary>
 [Trait("Category", "RequiresDocker")]
-public sealed class UserDataManagerReplicaTests : IAsyncLifetime
+public sealed class UserDataManagerReplicaTests : IClassFixture<UserDataManagerReplicaTests.DatabaseFixture>
 {
     private static readonly long _quarterIn = TimeSpan.FromMinutes(20).Ticks;
 
-    private PostgreSqlTestServer _server = null!;
+    private readonly NpgsqlDataSource _dataSource;
 
-    /// <inheritdoc/>
-    public async ValueTask InitializeAsync()
+    public UserDataManagerReplicaTests(DatabaseFixture fixture)
     {
-        _server = await PostgreSqlTestServer.StartAsync().ConfigureAwait(false);
-    }
-
-    /// <inheritdoc/>
-    public async ValueTask DisposeAsync()
-    {
-        await _server.DisposeAsync().ConfigureAwait(false);
+        _dataSource = fixture.DataSource;
     }
 
     /// <summary>
@@ -56,14 +50,11 @@ public sealed class UserDataManagerReplicaTests : IAsyncLifetime
     public async Task ResumePositionWrittenOnOneReplica_IsReadOnAnother()
     {
         var cancellationToken = TestContext.Current.CancellationToken;
-        var connectionString = await _server.CreateDatabaseAsync("userdata_replica_resume", cancellationToken);
-
-        await using var dataSource = new NpgsqlDataSourceBuilder(connectionString).Build();
         var itemId = Guid.NewGuid();
-        var user = await CreateSchemaWithUserAndItemAsync(dataSource, itemId, cancellationToken);
+        var user = await CreateUserAndItemAsync(_dataSource, itemId, cancellationToken);
 
-        var replicaA = CreateManager(dataSource);
-        var replicaB = CreateManager(dataSource);
+        var replicaA = CreateManager(_dataSource);
+        var replicaB = CreateManager(_dataSource);
         var itemOnA = new AudioBook { Id = itemId, Name = "Replica Book" };
         var itemOnB = new AudioBook { Id = itemId, Name = "Replica Book" };
 
@@ -72,7 +63,7 @@ public sealed class UserDataManagerReplicaTests : IAsyncLifetime
         replicaA.SaveUserData(user, itemOnA, early, UserDataSaveReason.PlaybackProgress, cancellationToken);
 
         // Replica B materialised the item before the later tick, so it holds the earlier row in memory.
-        itemOnB.UserData = await LoadUserDataAsync(dataSource, itemId, cancellationToken);
+        itemOnB.UserData = await LoadUserDataAsync(_dataSource, itemId, cancellationToken);
 
         var later = replicaA.GetUserData(user, itemOnA)!;
         later.PlaybackPositionTicks = _quarterIn;
@@ -91,14 +82,11 @@ public sealed class UserDataManagerReplicaTests : IAsyncLifetime
     public async Task PlaybackTickOnOneReplica_KeepsFavouriteSetOnAnother()
     {
         var cancellationToken = TestContext.Current.CancellationToken;
-        var connectionString = await _server.CreateDatabaseAsync("userdata_replica_favourite", cancellationToken);
-
-        await using var dataSource = new NpgsqlDataSourceBuilder(connectionString).Build();
         var itemId = Guid.NewGuid();
-        var user = await CreateSchemaWithUserAndItemAsync(dataSource, itemId, cancellationToken);
+        var user = await CreateUserAndItemAsync(_dataSource, itemId, cancellationToken);
 
-        var replicaA = CreateManager(dataSource);
-        var replicaB = CreateManager(dataSource);
+        var replicaA = CreateManager(_dataSource);
+        var replicaB = CreateManager(_dataSource);
         var itemOnA = new AudioBook { Id = itemId, Name = "Replica Book" };
         var itemOnB = new AudioBook { Id = itemId, Name = "Replica Book" };
 
@@ -107,7 +95,7 @@ public sealed class UserDataManagerReplicaTests : IAsyncLifetime
         replicaA.SaveUserData(user, itemOnA, seed, UserDataSaveReason.PlaybackProgress, cancellationToken);
 
         // Replica B is serving the playback session and read the item before the favourite was recorded.
-        itemOnB.UserData = await LoadUserDataAsync(dataSource, itemId, cancellationToken);
+        itemOnB.UserData = await LoadUserDataAsync(_dataSource, itemId, cancellationToken);
 
         var favourited = replicaA.GetUserData(user, itemOnA)!;
         favourited.IsFavorite = true;
@@ -131,14 +119,11 @@ public sealed class UserDataManagerReplicaTests : IAsyncLifetime
     public async Task PlaybackTickOnOneReplica_ResumesFromThePositionAnotherWrote()
     {
         var cancellationToken = TestContext.Current.CancellationToken;
-        var connectionString = await _server.CreateDatabaseAsync("userdata_replica_lost_update", cancellationToken);
-
-        await using var dataSource = new NpgsqlDataSourceBuilder(connectionString).Build();
         var itemId = Guid.NewGuid();
-        var user = await CreateSchemaWithUserAndItemAsync(dataSource, itemId, cancellationToken);
+        var user = await CreateUserAndItemAsync(_dataSource, itemId, cancellationToken);
 
-        var replicaA = CreateManager(dataSource);
-        var replicaB = CreateManager(dataSource);
+        var replicaA = CreateManager(_dataSource);
+        var replicaB = CreateManager(_dataSource);
         var itemOnA = new AudioBook { Id = itemId, Name = "Replica Book" };
         var itemOnB = new AudioBook { Id = itemId, Name = "Replica Book" };
 
@@ -146,7 +131,7 @@ public sealed class UserDataManagerReplicaTests : IAsyncLifetime
         seed.PlaybackPositionTicks = TimeSpan.FromMinutes(5).Ticks;
         replicaA.SaveUserData(user, itemOnA, seed, UserDataSaveReason.PlaybackProgress, cancellationToken);
 
-        itemOnB.UserData = await LoadUserDataAsync(dataSource, itemId, cancellationToken);
+        itemOnB.UserData = await LoadUserDataAsync(_dataSource, itemId, cancellationToken);
 
         // The viewer seeks forward and the tick reporting it lands on replica A.
         var seeked = replicaA.GetUserData(user, itemOnA)!;
@@ -182,14 +167,12 @@ public sealed class UserDataManagerReplicaTests : IAsyncLifetime
         }
     }
 
-    private static async Task<User> CreateSchemaWithUserAndItemAsync(NpgsqlDataSource dataSource, Guid itemId, CancellationToken cancellationToken)
+    private static async Task<User> CreateUserAndItemAsync(NpgsqlDataSource dataSource, Guid itemId, CancellationToken cancellationToken)
     {
         var context = CreateContext(dataSource);
         await using (context.ConfigureAwait(false))
         {
-            await context.Database.EnsureCreatedAsync(cancellationToken).ConfigureAwait(false);
-
-            var user = new User("replica-user", "provider", "provider");
+            var user = new User("replica-user-" + itemId.ToString("N", CultureInfo.InvariantCulture), "provider", "provider");
             context.Users.Add(user);
             context.BaseItems.Add(new BaseItemEntity { Id = itemId, Type = typeof(AudioBook).FullName! });
             await context.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
@@ -225,4 +208,36 @@ public sealed class UserDataManagerReplicaTests : IAsyncLifetime
 
         public JellyfinDbContext CreateDbContext() => CreateContext(_dataSource);
     }
+
+    /// <summary>
+    /// Builds the schema once for the whole class. Every test keeps to its own user and item, so one
+    /// database serves all of them and the shared server is spared three schema builds.
+    /// </summary>
+    public sealed class DatabaseFixture : IAsyncLifetime
+    {
+        private PostgreSqlTestServer _server = null!;
+
+        public NpgsqlDataSource DataSource { get; private set; } = null!;
+
+        /// <inheritdoc/>
+        public async ValueTask InitializeAsync()
+        {
+            _server = await PostgreSqlTestServer.StartAsync().ConfigureAwait(false);
+            var connectionString = await _server.CreateDatabaseAsync("userdata_replica", CancellationToken.None).ConfigureAwait(false);
+            DataSource = new NpgsqlDataSourceBuilder(connectionString).Build();
+
+            var context = CreateContext(DataSource);
+            await using (context.ConfigureAwait(false))
+            {
+                await context.Database.EnsureCreatedAsync(CancellationToken.None).ConfigureAwait(false);
+            }
+        }
+
+        /// <inheritdoc/>
+        public async ValueTask DisposeAsync()
+        {
+            await DataSource.DisposeAsync().ConfigureAwait(false);
+            await _server.DisposeAsync().ConfigureAwait(false);
+        }
+    }
 }