Add denormalized list of artist_ids to album, to speed-up artist's albums queries

This will be removed once we have a proper many-to-many relationship between album and artist

db/migration/20201213124814_add_all_artist_ids_to_album.go

@@ -0,0 +1,62 @@
+package migration
+
+import (
+	"database/sql"
+
+	"github.com/deluan/navidrome/log"
+	"github.com/deluan/navidrome/utils"
+	"github.com/pressly/goose"
+)
+
+func init() {
+	goose.AddMigration(Up20201213124814, Down20201213124814)
+}
+
+func Up20201213124814(tx *sql.Tx) error {
+	_, err := tx.Exec(`
+alter table album
+	add all_artist_ids varchar;
+
+create index if not exists album_all_artist_ids
+	on album (all_artist_ids);
+`)
+	if err != nil {
+		return err
+	}
+
+	return updateAlbums20201213124814(tx)
+}
+
+func updateAlbums20201213124814(tx *sql.Tx) error {
+	rows, err := tx.Query(`
+select a.id, a.name, a.artist_id, a.album_artist_id, group_concat(mf.artist_id, ' ') 
+       from album a left join media_file mf on a.id = mf.album_id group by a.id
+   `)
+	if err != nil {
+		return err
+	}
+	defer rows.Close()
+
+	stmt, err := tx.Prepare("update album set all_artist_ids = ? where id = ?")
+	if err != nil {
+		return err
+	}
+
+	var id, name, artistId, albumArtistId, songArtistIds string
+	for rows.Next() {
+		err := rows.Scan(&id, &name, &artistId, &albumArtistId, &songArtistIds)
+		if err != nil {
+			return err
+		}
+		all := utils.SanitizeStrings(artistId, albumArtistId, songArtistIds)
+		_, err = stmt.Exec(all, id)
+		if err != nil {
+			log.Error("Error setting album's artist_ids", "album", name, "albumId", id, err)
+		}
+	}
+	return rows.Err()
+}
+
+func Down20201213124814(tx *sql.Tx) error {
+	return nil
+}