perf(artwork): fetch only IDs for backfill enumeration

Backfill enumerated every album, artist, playlist and radio via GetAll
and mapped out just the ID. GetAll materializes full entities (library
joins, participant/stats/tags JSON, annotation, artwork hydration), so on
a large library it loaded tens of thousands of heavy structs only to read
one field each — spiking transient RSS to ~1GB during the one-time
upgrade backfill, a memory risk on small NAS/Pi hardware.

Add GetAllIDs to the album, artist, playlist and radio repositories: it
reuses each repo's base row-set filter (library visibility, artist
content join, playlist userFilter) but projects only id, skipping the
heavy columns and post-processing. A per-repo parity test asserts
GetAllIDs returns exactly the same id set as GetAll.

Verified on a 727MB / 29k-artist production DB copy: peak RSS during
backfill dropped from ~1012MB to ~89MB, file descriptors flat, same
36,138 items enqueued.

core/artwork/housekeeping.go

@@ -12,7 +12,6 @@ import (
 	"github.com/navidrome/navidrome/core/auth"
 	"github.com/navidrome/navidrome/log"
 	"github.com/navidrome/navidrome/model"
-	"github.com/navidrome/navidrome/utils/slice"
 )
 
 // FingerprintPropertyKey is the model.PropertyRepository key Backfill compares against
@@ -54,22 +53,10 @@ func Backfill(ctx context.Context, ds model.DataStore) (bool, error) {
 		kind  string
 		fetch func() ([]string, error)
 	}{
-		{"ar", func() ([]string, error) {
-			as, err := ds.Artist(ctx).GetAll()
-			return slice.Map(as, func(a model.Artist) string { return a.ID }), err
-		}},
-		{"al", func() ([]string, error) {
-			as, err := ds.Album(ctx).GetAll()
-			return slice.Map(as, func(a model.Album) string { return a.ID }), err
-		}},
-		{"pl", func() ([]string, error) {
-			ps, err := ds.Playlist(ctx).GetAll()
-			return slice.Map(ps, func(p model.Playlist) string { return p.ID }), err
-		}},
-		{"ra", func() ([]string, error) {
-			rs, err := ds.Radio(ctx).GetAll()
-			return slice.Map(rs, func(r model.Radio) string { return r.ID }), err
-		}},
+		{"ar", func() ([]string, error) { return ds.Artist(ctx).GetAllIDs() }},
+		{"al", func() ([]string, error) { return ds.Album(ctx).GetAllIDs() }},
+		{"pl", func() ([]string, error) { return ds.Playlist(ctx).GetAllIDs() }},
+		{"ra", func() ([]string, error) { return ds.Radio(ctx).GetAllIDs() }},
 	}
 	for _, k := range kinds {
 		ids, err := k.fetch()

model/album.go

@@ -142,6 +142,7 @@ type AlbumRepository interface {
 	UpdateExternalInfo(*Album) error
 	Get(id string) (*Album, error)
 	GetAll(...QueryOptions) (Albums, error)
+	GetAllIDs(...QueryOptions) ([]string, error)
 	GetCursor(...QueryOptions) (AlbumCursor, error)
 	GetYears(libraryIDs ...int) ([]int, error)
 

model/artist.go

@@ -89,6 +89,7 @@ type ArtistRepository interface {
 	UpdateExternalInfo(a *Artist) error
 	Get(id string) (*Artist, error)
 	GetAll(options ...QueryOptions) (Artists, error)
+	GetAllIDs(options ...QueryOptions) ([]string, error)
 	GetCursor(options ...QueryOptions) (ArtistCursor, error)
 	GetIndex(includeMissing bool, libraryIds []int, roles ...Role) (ArtistIndexes, error)
 

model/playlist.go

@@ -143,6 +143,7 @@ type PlaylistRepository interface {
 	Get(id string) (*Playlist, error)
 	GetWithTracks(id string, refreshSmartPlaylist, includeMissing bool) (*Playlist, error)
 	GetAll(options ...QueryOptions) (Playlists, error)
+	GetAllIDs(options ...QueryOptions) ([]string, error)
 	GetCursor(options ...QueryOptions) (PlaylistCursor, error)
 	FindByPath(path string) (*Playlist, error)
 	Delete(id string) error

model/radio.go

@@ -32,5 +32,6 @@ type RadioRepository interface {
 	Delete(id string) error
 	Get(id string) (*Radio, error)
 	GetAll(options ...QueryOptions) (Radios, error)
+	GetAllIDs(options ...QueryOptions) ([]string, error)
 	Put(u *Radio, colsToUpdate ...string) error
 }

persistence/album_repository.go

@@ -254,6 +254,15 @@ func (r *albumRepository) GetAll(options ...model.QueryOptions) (model.Albums, e
 	return res.toModels(), nil
 }
 
+// GetAllIDs returns just the album IDs for the same row set as GetAll, skipping the
+// heavy column projection and JSON post-processing. Used by bulk enumeration (artwork backfill).
+func (r *albumRepository) GetAllIDs(options ...model.QueryOptions) ([]string, error) {
+	sq := r.applyLibraryFilter(r.newSelect(options...).Columns("album.id"))
+	ids := []string{}
+	err := r.queryAllSlice(sq, &ids)
+	return ids, err
+}
+
 func (r *albumRepository) GetCursor(options ...model.QueryOptions) (model.AlbumCursor, error) {
 	sq := r.selectAlbum(options...)
 	cursor, err := queryWithStableResults[dbAlbum](r.sqlRepository, sq)

persistence/album_repository_test.go

@@ -84,6 +84,21 @@ var _ = Describe("AlbumRepository", func() {
 		})
 	})
 
+	Describe("GetAllIDs", func() {
+		It("returns the same id set as GetAll", func() {
+			want, err := albumRepo.GetAll()
+			Expect(err).ToNot(HaveOccurred())
+			Expect(want).ToNot(BeEmpty())
+			wantIDs := make([]string, 0, len(want))
+			for _, a := range want {
+				wantIDs = append(wantIDs, a.ID)
+			}
+			ids, err := albumRepo.GetAllIDs()
+			Expect(err).ToNot(HaveOccurred())
+			Expect(ids).To(ConsistOf(wantIDs))
+		})
+	})
+
 	Describe("GetAll", func() {
 		var GetAll = func(opts ...model.QueryOptions) (model.Albums, error) {
 			albums, err := albumRepo.GetAll(opts...)

persistence/artist_repository.go

@@ -264,6 +264,15 @@ func (r *artistRepository) GetAll(options ...model.QueryOptions) (model.Artists,
 	return res, err
 }
 
+// GetAllIDs returns just the artist IDs for the same row set as GetAll, skipping the
+// heavy stats/annotation columns and JSON post-processing. Used by bulk enumeration (artwork backfill).
+func (r *artistRepository) GetAllIDs(options ...model.QueryOptions) ([]string, error) {
+	sq := r.applyLibraryFilterToArtistQuery(r.newSelect(options...).Columns("artist.id")).GroupBy("artist.id")
+	ids := []string{}
+	err := r.queryAllSlice(sq, &ids)
+	return ids, err
+}
+
 func (r *artistRepository) GetCursor(options ...model.QueryOptions) (model.ArtistCursor, error) {
 	sel := r.selectArtist(options...)
 	cursor, err := queryWithStableResults[dbArtist](r.sqlRepository, sel)

persistence/artist_repository_test.go

@@ -284,6 +284,21 @@ var _ = Describe("ArtistRepository", func() {
 			})
 		})
 
+		Describe("GetAllIDs", func() {
+			It("returns the same id set as GetAll", func() {
+				want, err := repo.GetAll()
+				Expect(err).ToNot(HaveOccurred())
+				Expect(want).ToNot(BeEmpty())
+				wantIDs := make([]string, 0, len(want))
+				for _, a := range want {
+					wantIDs = append(wantIDs, a.ID)
+				}
+				ids, err := repo.GetAllIDs()
+				Expect(err).ToNot(HaveOccurred())
+				Expect(ids).To(ConsistOf(wantIDs))
+			})
+		})
+
 		Describe("Basic Operations", func() {
 			Describe("Count", func() {
 				It("returns the number of artists in the DB", func() {

persistence/playlist_repository.go

@@ -189,6 +189,16 @@ func (r *playlistRepository) GetAll(options ...model.QueryOptions) (model.Playli
 	return playlists, err
 }
 
+// GetAllIDs returns just the playlist IDs for the same row set as GetAll (honoring userFilter),
+// skipping the owner-name join columns and annotation. Used by bulk enumeration (artwork backfill).
+func (r *playlistRepository) GetAllIDs(options ...model.QueryOptions) ([]string, error) {
+	sq := r.newSelect(options...).Columns("playlist.id").
+		Join("user on user.id = owner_id").Where(r.userFilter())
+	ids := []string{}
+	err := r.queryAllSlice(sq, &ids)
+	return ids, err
+}
+
 func (r *playlistRepository) GetCursor(options ...model.QueryOptions) (model.PlaylistCursor, error) {
 	// Same userFilter as GetAll: a cursor must not widen visibility beyond public/owned playlists.
 	sel := r.selectPlaylist(options...).Where(r.userFilter())

persistence/playlist_repository_test.go

@@ -37,6 +37,21 @@ var _ = Describe("PlaylistRepository", func() {
 		})
 	})
 
+	Describe("GetAllIDs", func() {
+		It("returns the same id set as GetAll", func() {
+			want, err := repo.GetAll()
+			Expect(err).ToNot(HaveOccurred())
+			Expect(want).ToNot(BeEmpty())
+			wantIDs := make([]string, 0, len(want))
+			for _, p := range want {
+				wantIDs = append(wantIDs, p.ID)
+			}
+			ids, err := repo.GetAllIDs()
+			Expect(err).ToNot(HaveOccurred())
+			Expect(ids).To(ConsistOf(wantIDs))
+		})
+	})
+
 	Describe("Exists", func() {
 		It("returns true for an existing playlist", func() {
 			Expect(repo.Exists(plsCool.ID)).To(BeTrue())

persistence/radio_repository.go

@@ -59,6 +59,14 @@ func (r *radioRepository) GetAll(options ...model.QueryOptions) (model.Radios, e
 	return res, err
 }
 
+// GetAllIDs returns just the radio IDs. Used by bulk enumeration (artwork backfill).
+func (r *radioRepository) GetAllIDs(options ...model.QueryOptions) ([]string, error) {
+	sel := r.newSelect(options...).Columns("id")
+	ids := []string{}
+	err := r.queryAllSlice(sel, &ids)
+	return ids, err
+}
+
 func (r *radioRepository) Put(radio *model.Radio, colsToUpdate ...string) error {
 	if !r.isPermitted() {
 		return rest.ErrPermissionDenied

persistence/radio_repository_test.go

@@ -78,6 +78,21 @@ var _ = Describe("RadioRepository", func() {
 			})
 		})
 
+		Describe("GetAllIDs", func() {
+			It("returns the same id set as GetAll", func() {
+				want, err := repo.GetAll()
+				Expect(err).To(BeNil())
+				Expect(want).ToNot(BeEmpty())
+				wantIDs := make([]string, 0, len(want))
+				for _, r := range want {
+					wantIDs = append(wantIDs, r.ID)
+				}
+				ids, err := repo.GetAllIDs()
+				Expect(err).To(BeNil())
+				Expect(ids).To(ConsistOf(wantIDs))
+			})
+		})
+
 		Describe("Put", func() {
 			It("successfully updates item", func() {
 				err := repo.Put(&model.Radio{

tests/mock_album_repo.go

@@ -76,6 +76,18 @@ func (m *MockAlbumRepo) GetAll(qo ...model.QueryOptions) (model.Albums, error) {
 	return m.All, nil
 }
 
+func (m *MockAlbumRepo) GetAllIDs(qo ...model.QueryOptions) ([]string, error) {
+	all, err := m.GetAll(qo...)
+	if err != nil {
+		return nil, err
+	}
+	ids := make([]string, len(all))
+	for i, a := range all {
+		ids[i] = a.ID
+	}
+	return ids, nil
+}
+
 func (m *MockAlbumRepo) GetCursor(qo ...model.QueryOptions) (model.AlbumCursor, error) {
 	res, err := m.GetAll(qo...)
 	if err != nil {

tests/mock_artist_repo.go

@@ -113,6 +113,18 @@ func (m *MockArtistRepo) GetAll(options ...model.QueryOptions) (model.Artists, e
 	return allArtists, nil
 }
 
+func (m *MockArtistRepo) GetAllIDs(options ...model.QueryOptions) ([]string, error) {
+	all, err := m.GetAll(options...)
+	if err != nil {
+		return nil, err
+	}
+	ids := make([]string, len(all))
+	for i, a := range all {
+		ids[i] = a.ID
+	}
+	return ids, nil
+}
+
 func (m *MockArtistRepo) GetCursor(options ...model.QueryOptions) (model.ArtistCursor, error) {
 	res, err := m.GetAll(options...)
 	if err != nil {

tests/mock_playlist_repo.go

@@ -52,6 +52,18 @@ func (m *MockPlaylistRepo) GetAll(options ...model.QueryOptions) (model.Playlist
 	return m.All, nil
 }
 
+func (m *MockPlaylistRepo) GetAllIDs(options ...model.QueryOptions) ([]string, error) {
+	all, err := m.GetAll(options...)
+	if err != nil {
+		return nil, err
+	}
+	ids := make([]string, len(all))
+	for i, p := range all {
+		ids[i] = p.ID
+	}
+	return ids, nil
+}
+
 func (m *MockPlaylistRepo) GetCursor(options ...model.QueryOptions) (model.PlaylistCursor, error) {
 	res, err := m.GetAll(options...)
 	if err != nil {

tests/mock_radio_repository.go

@@ -73,6 +73,18 @@ func (m *MockedRadioRepo) GetAll(qo ...model.QueryOptions) (model.Radios, error)
 	return m.All, nil
 }
 
+func (m *MockedRadioRepo) GetAllIDs(qo ...model.QueryOptions) ([]string, error) {
+	all, err := m.GetAll(qo...)
+	if err != nil {
+		return nil, err
+	}
+	ids := make([]string, len(all))
+	for i, r := range all {
+		ids[i] = r.ID
+	}
+	return ids, nil
+}
+
 func (m *MockedRadioRepo) Put(radio *model.Radio, _ ...string) error {
 	if m.Err {
 		return errors.New("error")