Jellyfin.Server.Implementations/Item/BaseItemRepository.ByName.cs

@@ -219,9 +219,11 @@ public sealed partial class BaseItemRepository
         }
         else
         {
+            // The representative is the row no other row in its group sorts before, not MIN(Id):
+            // PostgreSQL has no min(uuid) aggregate, while comparing two uuids is supported everywhere.
             representativeIds = masterQuery
-                .GroupBy(e => e.PresentationUniqueKey)
-                .Select(g => g.Min(e => e.Id))
+                .Where(e => !masterQuery.Any(o => o.PresentationUniqueKey == e.PresentationUniqueKey && o.Id.CompareTo(e.Id) < 0))
+                .Select(e => e.Id)
                 .ToList();
         }
 

Jellyfin.Server.Implementations/Item/BaseItemRepository.QueryBuilding.cs

@@ -96,22 +96,36 @@ public sealed partial class BaseItemRepository
         // primary version (PrimaryVersionId is null) so detail pages and actions target it instead
         // of an arbitrary alternate. Keep the grouped ids as an IQueryable sub-select; materializing
         // to a List would inline one bound parameter per id and hit SQLite's variable cap.
+        // The representative is the row no other row in its group sorts before, not MIN(Id):
+        // PostgreSQL has no min(uuid) aggregate, while comparing two uuids is supported everywhere.
+        // The anti-join reads the filtered set twice, so it has to close over a local that the
+        // reassignment below cannot reach - capturing dbQuery itself makes the tree self-referential.
+        var candidates = dbQuery;
         var enableGroupByPresentationUniqueKey = EnableGroupByPresentationUniqueKey(filter);
         if (enableGroupByPresentationUniqueKey && filter.GroupBySeriesPresentationUniqueKey)
         {
-            var groupedIds = dbQuery.GroupBy(e => new { e.PresentationUniqueKey, e.SeriesPresentationUniqueKey })
-                .Select(g => g.Where(e => e.PrimaryVersionId == null).Min(e => (Guid?)e.Id) ?? g.Min(e => (Guid?)e.Id));
+            var groupedIds = candidates
+                .Where(e => !candidates.Any(o => o.PresentationUniqueKey == e.PresentationUniqueKey
+                    && o.SeriesPresentationUniqueKey == e.SeriesPresentationUniqueKey
+                    && ((o.PrimaryVersionId == null && e.PrimaryVersionId != null)
+                        || ((o.PrimaryVersionId == null) == (e.PrimaryVersionId == null) && o.Id.CompareTo(e.Id) < 0))))
+                .Select(e => e.Id);
             dbQuery = context.BaseItems.AsNoTracking().Where(e => groupedIds.Contains(e.Id));
         }
         else if (enableGroupByPresentationUniqueKey)
         {
-            var groupedIds = dbQuery.GroupBy(e => e.PresentationUniqueKey)
-                .Select(g => g.Where(e => e.PrimaryVersionId == null).Min(e => (Guid?)e.Id) ?? g.Min(e => (Guid?)e.Id));
+            var groupedIds = candidates
+                .Where(e => !candidates.Any(o => o.PresentationUniqueKey == e.PresentationUniqueKey
+                    && ((o.PrimaryVersionId == null && e.PrimaryVersionId != null)
+                        || ((o.PrimaryVersionId == null) == (e.PrimaryVersionId == null) && o.Id.CompareTo(e.Id) < 0))))
+                .Select(e => e.Id);
             dbQuery = context.BaseItems.AsNoTracking().Where(e => groupedIds.Contains(e.Id));
         }
         else if (filter.GroupBySeriesPresentationUniqueKey)
         {
-            var groupedIds = dbQuery.GroupBy(e => e.SeriesPresentationUniqueKey).Select(e => e.Min(x => x.Id));
+            var groupedIds = candidates
+                .Where(e => !candidates.Any(o => o.SeriesPresentationUniqueKey == e.SeriesPresentationUniqueKey && o.Id.CompareTo(e.Id) < 0))
+                .Select(e => e.Id);
             dbQuery = context.BaseItems.AsNoTracking().Where(e => groupedIds.Contains(e.Id));
         }
         else

tests/Jellyfin.Server.Tests/Item/PostgreSqlPresentationKeyGroupingTests.cs

@@ -0,0 +1,213 @@
+using System;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using Emby.Server.Implementations.Data;
+using Jellyfin.Database.Implementations;
+using Jellyfin.Database.Implementations.DbConfiguration;
+using Jellyfin.Database.Implementations.Entities;
+using Jellyfin.Database.Implementations.Locking;
+using Jellyfin.Database.Providers.PostgreSQL;
+using Jellyfin.Server.Implementations.Item;
+using Jellyfin.Server.Tests.Migrations;
+using MediaBrowser.Controller;
+using MediaBrowser.Controller.Configuration;
+using MediaBrowser.Controller.Entities;
+using MediaBrowser.Model.Configuration;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging.Abstractions;
+using Moq;
+using Npgsql;
+using Xunit;
+using BaseItemKind = Jellyfin.Data.Enums.BaseItemKind;
+using User = Jellyfin.Database.Implementations.Entities.User;
+
+namespace Jellyfin.Server.Tests.Item;
+
+/// <summary>
+/// Runs the presentation-key collapse that library browse, search and the by-name endpoints all go
+/// through against a real PostgreSQL. SQLite accepts <c>MIN</c> over any column type, PostgreSQL has no
+/// <c>min(uuid)</c> aggregate, so a representative picked with an aggregate over the id only ever fails
+/// here - with <c>42883 function min(uuid) does not exist</c>.
+/// </summary>
+[Trait("Category", "RequiresDocker")]
+public sealed class PostgreSqlPresentationKeyGroupingTests : IAsyncLifetime
+{
+    // The alternate sorts before the primary, and the second duplicate genre before the first, so a
+    // representative that ignores the primary-version preference or the id order picks the wrong row.
+    private static readonly Guid _primaryMovieId = Guid.Parse("eeeeeeee-0000-0000-0000-000000000001");
+    private static readonly Guid _alternateMovieId = Guid.Parse("11111111-0000-0000-0000-000000000002");
+    private static readonly Guid _secondAlternateMovieId = Guid.Parse("22222222-0000-0000-0000-000000000003");
+    private static readonly Guid _firstOrphanId = Guid.Parse("33333333-0000-0000-0000-000000000004");
+    private static readonly Guid _secondOrphanId = Guid.Parse("dddddddd-0000-0000-0000-000000000005");
+    private static readonly Guid _orphanPrimaryId = Guid.Parse("cccccccc-0000-0000-0000-000000000006");
+    private static readonly Guid _standaloneMovieId = Guid.Parse("44444444-0000-0000-0000-000000000007");
+
+    private static readonly Guid _firstGenreId = Guid.Parse("bbbbbbbb-0000-0000-0000-000000000001");
+    private static readonly Guid _secondGenreId = Guid.Parse("aaaaaaaa-0000-0000-0000-000000000002");
+    private static readonly Guid _genreMovieId = Guid.Parse("66666666-0000-0000-0000-000000000003");
+    private static readonly Guid _genreValueId = Guid.Parse("77777777-0000-0000-0000-000000000004");
+
+    private readonly ItemTypeLookup _itemTypeLookup = new();
+
+    private PostgreSqlTestServer _server = null!;
+    private NpgsqlDataSource _dataSource = null!;
+    private BaseItemRepository _repository = null!;
+
+    public async ValueTask InitializeAsync()
+    {
+        _server = await PostgreSqlTestServer.StartAsync().ConfigureAwait(false);
+        var connectionString = await _server.CreateDatabaseAsync("presentation_key_grouping", TestContext.Current.CancellationToken).ConfigureAwait(false);
+        _dataSource = new NpgsqlDataSourceBuilder(connectionString).Build();
+
+        var context = CreateDbContext();
+        await using (context.ConfigureAwait(false))
+        {
+            await context.Database.EnsureCreatedAsync(TestContext.Current.CancellationToken).ConfigureAwait(false);
+        }
+
+        var serverConfigurationManager = new Mock<IServerConfigurationManager>();
+        serverConfigurationManager.Setup(c => c.Configuration).Returns(new ServerConfiguration());
+
+        var factory = new Mock<IDbContextFactory<JellyfinDbContext>>();
+        factory.Setup(f => f.CreateDbContext()).Returns(CreateDbContext);
+        factory.Setup(f => f.CreateDbContextAsync(It.IsAny<CancellationToken>())).ReturnsAsync(CreateDbContext);
+
+        _repository = new BaseItemRepository(
+            factory.Object,
+            new Mock<IServerApplicationHost>().Object,
+            _itemTypeLookup,
+            serverConfigurationManager.Object,
+            NullLogger<BaseItemRepository>.Instance);
+
+        await SeedAsync().ConfigureAwait(false);
+    }
+
+    public async ValueTask DisposeAsync()
+    {
+        await _dataSource.DisposeAsync().ConfigureAwait(false);
+        await _server.DisposeAsync().ConfigureAwait(false);
+    }
+
+    /// <summary>
+    /// The collapse behind library browse and search: one row per presentation key, the primary version
+    /// when the group has one, the lowest id otherwise.
+    /// </summary>
+    [Fact]
+    public void GetItemList_CollapsesPresentationKeyGroups()
+    {
+        var items = _repository.GetItemList(new InternalItemsQuery(new User("grouping", "auth", "reset"))
+        {
+            IncludeItemTypes = [BaseItemKind.Movie],
+            IncludeOwnedItems = true
+        });
+
+        Assert.Equal(
+            new[] { _primaryMovieId, _firstOrphanId, _standaloneMovieId, _genreMovieId }.OrderBy(id => id).ToArray(),
+            items.Select(i => i.Id).OrderBy(id => id).ToArray());
+    }
+
+    /// <summary>
+    /// The same collapse on the by-name path, which picks the lowest id per group without a
+    /// primary-version preference.
+    /// </summary>
+    [Fact]
+    public void GetGenres_CollapsesPresentationKeyGroups()
+    {
+        var result = _repository.GetGenres(new InternalItemsQuery(new User("genres", "auth", "reset")));
+
+        var item = Assert.Single(result.Items);
+        Assert.Equal(_secondGenreId, item.Item.Id);
+        Assert.Equal(1, result.TotalRecordCount);
+    }
+
+    private JellyfinDbContext CreateDbContext()
+    {
+        var optionsBuilder = new DbContextOptionsBuilder<JellyfinDbContext>();
+        var provider = new PostgreSqlDatabaseProvider(_dataSource);
+        provider.Initialise(optionsBuilder, new DatabaseConfigurationOptions { DatabaseType = "PostgreSQL" });
+        return new JellyfinDbContext(
+            optionsBuilder.Options,
+            NullLogger<JellyfinDbContext>.Instance,
+            provider,
+            new NoLockBehavior(NullLogger<NoLockBehavior>.Instance));
+    }
+
+    private async Task SeedAsync()
+    {
+        var context = CreateDbContext();
+        await using (context.ConfigureAwait(false))
+        {
+            // One version group: a primary plus two alternates, both sorting before it by id.
+            var versionKey = _primaryMovieId.ToString("N");
+            context.BaseItems.Add(CreateMovie(_primaryMovieId, "Movie", versionKey, null));
+            context.BaseItems.Add(CreateMovie(_alternateMovieId, "Movie - 1080p", versionKey, _primaryMovieId));
+            context.BaseItems.Add(CreateMovie(_secondAlternateMovieId, "Movie - 4K", versionKey, _primaryMovieId));
+
+            // One group whose primary is not in the result set, so the lowest id represents it.
+            var orphanKey = _orphanPrimaryId.ToString("N");
+            context.BaseItems.Add(CreateMovie(_firstOrphanId, "Orphan - 1080p", orphanKey, _orphanPrimaryId));
+            context.BaseItems.Add(CreateMovie(_secondOrphanId, "Orphan - 4K", orphanKey, _orphanPrimaryId));
+
+            context.BaseItems.Add(CreateMovie(_standaloneMovieId, "Standalone", _standaloneMovieId.ToString("N"), null));
+
+            // Two genre entities sharing a presentation key, credited on one movie so the by-name
+            // item-value join sees them.
+            var genreKey = _firstGenreId.ToString("N");
+            context.BaseItems.Add(CreateGenre(_firstGenreId, "Action", genreKey));
+            context.BaseItems.Add(CreateGenre(_secondGenreId, "Action", genreKey));
+
+            var genreMovie = CreateMovie(_genreMovieId, "Genre Movie", _genreMovieId.ToString("N"), null);
+            genreMovie.CleanName = "genre movie";
+            context.BaseItems.Add(genreMovie);
+
+            var genreValue = new ItemValue
+            {
+                ItemValueId = _genreValueId,
+                Type = ItemValueType.Genre,
+                Value = "Action",
+                CleanValue = "action"
+            };
+            context.ItemValues.Add(genreValue);
+            context.ItemValuesMap.Add(new ItemValueMap
+            {
+                ItemId = _genreMovieId,
+                ItemValueId = _genreValueId,
+                Item = genreMovie,
+                ItemValue = genreValue
+            });
+
+            await context.SaveChangesAsync(TestContext.Current.CancellationToken).ConfigureAwait(false);
+        }
+    }
+
+    private BaseItemEntity CreateMovie(Guid id, string name, string presentationKey, Guid? primaryVersionId)
+    {
+        return new BaseItemEntity
+        {
+            Id = id,
+            Type = _itemTypeLookup.BaseItemKindNames[BaseItemKind.Movie],
+            Name = name,
+            PresentationUniqueKey = presentationKey,
+            PrimaryVersionId = primaryVersionId,
+            MediaType = "Video",
+            IsMovie = true,
+            IsFolder = false,
+            IsVirtualItem = false
+        };
+    }
+
+    private BaseItemEntity CreateGenre(Guid id, string name, string presentationKey)
+    {
+        return new BaseItemEntity
+        {
+            Id = id,
+            Type = _itemTypeLookup.BaseItemKindNames[BaseItemKind.Genre],
+            Name = name,
+            CleanName = "action",
+            PresentationUniqueKey = presentationKey,
+            IsFolder = false,
+            IsVirtualItem = false
+        };
+    }
+}