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Optimize querying for missing albums

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| Problem                  | Cause                                                      |
|--------------------------|------------------------------------------------------------|
| High row count           | selecting rows before grouping and sorting                 |
| Large sort in memory     | GB of memory used for low millions of records w/ quicksort |
| Expensive Anti Join      | On `TrackFiles.Id IS NULL` condition                       |
| Grouping before LIMIT    | Entire result grouped before applying LIMIT+OFFSET         |
This commit is contained in:
Jack Danger 2025-04-06 12:25:44 -07:00
parent 4677a1115a
commit 92cf3546e6
1 changed files with 16 additions and 12 deletions
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28
src/NzbDrone.Core/Music/Repositories/AlbumRepository.cs
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@ -90,22 +90,26 @@ namespace NzbDrone.Core.Music
return Query(s => s.ForeignAlbumId == foreignAlbumId).SingleOrDefault();
}
// x.Id == null is converted to SQL, so warning incorrect
#pragma warning disable CS0472
private SqlBuilder AlbumsWithoutFilesBuilder(DateTime currentTime)
{
// First, create a subquery to find albums with missing tracks
var missingTracksSubquery = Builder()
.Select("\"AlbumReleases\".\"AlbumId\"")
.Join<AlbumRelease, Track>((r, t) => r.Id == t.AlbumReleaseId)
.LeftJoin<Track, TrackFile>((t, f) => t.TrackFileId == f.Id)
.Where<TrackFile>(f => f == null)
.Where<AlbumRelease>(r => r.Monitored == true)
.GroupBy("\"AlbumReleases\".\"AlbumId\"");
// Main query that joins with the subquery
return Builder()
.Join<Album, Artist>((l, r) => l.ArtistMetadataId == r.ArtistMetadataId)
.Join<Album, AlbumRelease>((a, r) => a.Id == r.AlbumId)
.Join<AlbumRelease, Track>((r, t) => r.Id == t.AlbumReleaseId)
.LeftJoin<Track, TrackFile>((t, f) => t.TrackFileId == f.Id)
.Where<TrackFile>(f => f.Id == null)
.Where<AlbumRelease>(r => r.Monitored == true)
.Where<Album>(a => a.ReleaseDate <= currentTime)
.GroupBy<Album>(x => x.Id)
.GroupBy<Artist>(x => x.SortName);
.Join<Album, Artist>((l, r) => l.ArtistMetadataId == r.ArtistMetadataId)
.Where<Album>(a => a.Monitored == true && a.ReleaseDate <= currentTime)
.Where<Artist>(a => a.Monitored == true)
.Where("\"Albums\".\"Id\" IN (SELECT \"AlbumReleases\".\"AlbumId\" FROM \"AlbumReleases\" JOIN \"Tracks\" ON (\"AlbumReleases\".\"Id\" = \"Tracks\".\"AlbumReleaseId\") LEFT JOIN \"TrackFiles\" ON (\"Tracks\".\"TrackFileId\" = \"TrackFiles\".\"Id\") WHERE \"TrackFiles\" IS NULL AND \"AlbumReleases\".\"Monitored\" = true GROUP BY \"AlbumReleases\".\"AlbumId\")")
.GroupBy<Album>(x => x.Id)
.GroupBy<Artist>(x => x.SortName);
}
#pragma warning restore CS0472
public PagingSpec<Album> AlbumsWithoutFiles(PagingSpec<Album> pagingSpec)
{