Fix DatePlayed sorting performance

2 files changed, 32 insertions, 18 deletions

diff --git a/Jellyfin.Server.Implementations/Item/BaseItemRepository.TranslateQuery.cs b/Jellyfin.Server.Implementations/Item/BaseItemRepository.TranslateQuery.cs
index f19df6259e..de25e9b763 100644
--- a/Jellyfin.Server.Implementations/Item/BaseItemRepository.TranslateQuery.cs
+++ b/Jellyfin.Server.Implementations/Item/BaseItemRepository.TranslateQuery.cs
@@ -560,16 +560,19 @@ public sealed partial class BaseItemRepository
                 // Only in-progress siblings can eliminate a candidate: a version without progress has a NULL max LastPlayedDate,
                 // which is never greater and never ties. Restricting the sibling scan to the in-progress set keeps this bounded by
                 // the user's Continue Watching count instead of forcing a full BaseItems scan (COALESCE keys are non-indexable) per row.
-                baseQuery = baseQuery.Where(e => e.Type == seriesTypeName || !context.BaseItems
-                    .Where(s => s.Id != e.Id
-                        && inProgressIds.Contains(s.Id)
-                        && (s.PrimaryVersionId ?? s.Id) == (e.PrimaryVersionId ?? e.Id))
-                    .Any(s =>
-                        inProgress.Where(su => su.ItemId == s.Id).Max(su => su.LastPlayedDate)
-                            > inProgress.Where(eu => eu.ItemId == e.Id).Max(eu => eu.LastPlayedDate)
-                        || (inProgress.Where(su => su.ItemId == s.Id).Max(su => su.LastPlayedDate)
-                                == inProgress.Where(eu => eu.ItemId == e.Id).Max(eu => eu.LastPlayedDate)
-                            && s.Id.CompareTo(e.Id) < 0)));
+                // Items in no version group at all have no sibling that could eliminate them, so short-circuit the scan for those.
+                baseQuery = baseQuery.Where(e => e.Type == seriesTypeName
+                    || (e.PrimaryVersionId == null && !context.BaseItems.Any(a => a.PrimaryVersionId == e.Id))
+                    || !context.BaseItems
+                        .Where(s => s.Id != e.Id
+                            && inProgressIds.Contains(s.Id)
+                            && (s.PrimaryVersionId ?? s.Id) == (e.PrimaryVersionId ?? e.Id))
+                        .Any(s =>
+                            inProgress.Where(su => su.ItemId == s.Id).Max(su => su.LastPlayedDate)
+                                > inProgress.Where(eu => eu.ItemId == e.Id).Max(eu => eu.LastPlayedDate)
+                            || (inProgress.Where(su => su.ItemId == s.Id).Max(su => su.LastPlayedDate)
+                                    == inProgress.Where(eu => eu.ItemId == e.Id).Max(eu => eu.LastPlayedDate)
+                                && s.Id.CompareTo(e.Id) < 0)));
             }
             else
             {
diff --git a/Jellyfin.Server.Implementations/Item/OrderMapper.cs b/Jellyfin.Server.Implementations/Item/OrderMapper.cs
index aac85d0131..25ad81ec6c 100644
--- a/Jellyfin.Server.Implementations/Item/OrderMapper.cs
+++ b/Jellyfin.Server.Implementations/Item/OrderMapper.cs
@@ -29,19 +29,30 @@ public static class OrderMapper
     /// <returns>Func to be executed later for sorting query.</returns>
     public static Expression<Func<BaseItemEntity, object?>> MapOrderByField(ItemSortBy sortBy, InternalItemsQuery query, JellyfinDbContext jellyfinDbContext)
     {
+        if (sortBy == ItemSortBy.DatePlayed)
+        {
+            // An item's played date is the newest of its own progress and that of its alternate versions,
+            // which track progress under their own ids. Matching both in one predicate ORs them together,
+            // which no index can serve: the user's whole UserData table gets scanned per sorted row.
+            // Two indexed lookups combined by MAX cost a seek each instead.
+            var userData = query.User is null
+                ? jellyfinDbContext.UserData
+                : jellyfinDbContext.UserData.Where(w => w.UserId == query.User.Id);
+
+            return e => userData
+                .Where(w => w.ItemId == e.Id)
+                .Select(w => w.LastPlayedDate)
+                .Concat(userData
+                    .Where(w => w.Item!.PrimaryVersionId == e.Id)
+                    .Select(w => w.LastPlayedDate))
+                .Max();
+        }
+
         return (sortBy, query.User) switch
         {
             (ItemSortBy.AirTime, _) => e => e.SortName,
             (ItemSortBy.Runtime, _) => e => e.RunTimeTicks,
             (ItemSortBy.Random, _) => e => EF.Functions.Random(),
-            (ItemSortBy.DatePlayed, not null) => e =>
-                jellyfinDbContext.UserData
-                    .Where(w => w.UserId == query.User.Id && (w.ItemId == e.Id || w.Item!.PrimaryVersionId == e.Id))
-                    .Max(f => f.LastPlayedDate),
-            (ItemSortBy.DatePlayed, null) => e =>
-                jellyfinDbContext.UserData
-                    .Where(w => w.ItemId == e.Id || w.Item!.PrimaryVersionId == e.Id)
-                    .Max(f => f.LastPlayedDate),
             (ItemSortBy.PlayCount, _) => e => e.UserData!.Where(f => f.UserId.Equals(query.User!.Id)).OrderBy(f => f.CustomDataKey).FirstOrDefault()!.PlayCount,
             (ItemSortBy.IsFavoriteOrLiked, _) => e => e.UserData!.Where(f => f.UserId.Equals(query.User!.Id)).OrderBy(f => f.CustomDataKey).Select(f => (bool?)f.IsFavorite).FirstOrDefault() ?? false,
             (ItemSortBy.IsFolder, _) => e => e.IsFolder,