Add notes around scrobble activity query optimization
This commit is contained in:
Claudio Ortolina
@@ -0,0 +1,264 @@
|
||||
╭─────────────────────────────────────────────────────────╮
|
||||
│ ✻ Welcome to Claude Code! │
|
||||
│ │
|
||||
│ /help for help, /status for your current setup │
|
||||
│ │
|
||||
│ cwd: /Users/cloud/github.com/cloud8421/music_library │
|
||||
╰─────────────────────────────────────────────────────────╯
|
||||
|
||||
> Can you optimize this query?
|
||||
|
||||
SELECT s0."scrobbled_at_uts", s0."musicbrainz_id", s0."title", s0."cover_url", s0."scrobbled_at_label", s0."artist", s0."album",
|
||||
s0."last_fm_data", s1."record_id", s2."record_id", s3."musicbrainz_id", coalesce(s1."cover_hash", s2."cover_hash") FROM
|
||||
"scrobbled_tracks" AS s0 LEFT OUTER JOIN (SELECT records.id AS "record_id", records.cover_hash AS "cover_hash", sf0."value" AS
|
||||
"release_id" FROM records, json_each(records.release_ids) AS sf0 WHERE (records.purchased_at IS NOT NULL)) AS s1 ON
|
||||
s1."release_id" = s0."album" ->> '$.musicbrainz_id' LEFT OUTER JOIN (SELECT records.id AS "record_id", records.cover_hash AS
|
||||
"cover_hash", sf0."value" AS "release_id" FROM records, json_each(records.release_ids) AS sf0 WHERE (records.purchased_at IS
|
||||
NULL)) AS s2 ON s2."release_id" = s0."album" ->> '$.musicbrainz_id' LEFT OUTER JOIN (SELECT DISTINCT sa0."musicbrainz_id" AS
|
||||
"musicbrainz_id", sa0."record_id" AS "record_id", sa0."artist" AS "artist" FROM "artist_records" AS sa0) AS s3 ON (s2."record_id"
|
||||
= s3."record_id") OR (s1."record_id" = s3."record_id") ORDER BY s0."scrobbled_at_uts" DESC LIMIT 100
|
||||
|
||||
⏺ I'll analyze this query to identify optimization opportunities. Let me first examine the current database schema and understand
|
||||
the query structure.
|
||||
⎿ * LastFm.Album at lib/last_fm/album.ex:1
|
||||
* LastFm.Artist at lib/last_fm/artist.ex:1
|
||||
* LastFm.Track at lib/last_fm/track.ex:1
|
||||
… +11 lines (ctrl+o to expand)
|
||||
|
||||
⏺ Search(pattern: "scrobbled_tracks")
|
||||
⎿ Found 11 files (ctrl+o to expand)
|
||||
|
||||
⏺ Read(lib/last_fm/track.ex)
|
||||
⎿ Read 95 lines (ctrl+o to expand)
|
||||
|
||||
⏺ Read(priv/repo/migrations/20250530203701_create_scrobbled_tracks.exs)
|
||||
⎿ Read 19 lines (ctrl+o to expand)
|
||||
|
||||
⏺ Read(lib/music_library/records/record.ex)
|
||||
⎿ Read 276 lines (ctrl+o to expand)
|
||||
|
||||
⏺ Now let me find where this query is being generated to understand the context:
|
||||
|
||||
⏺ Search(pattern: "FROM.*scrobbled_tracks.*AS s0")
|
||||
⎿ Found 0 files
|
||||
|
||||
⏺ Search(pattern: "scrobbled_tracks.*LEFT OUTER JOIN", output_mode: "content")
|
||||
⎿ Found 0 lines
|
||||
|
||||
⏺ Search(pattern: "json_each.*release_ids")
|
||||
⎿ Found 3 files (ctrl+o to expand)
|
||||
|
||||
⏺ Search(pattern: "scrobbled_tracks.*s0", output_mode: "content")
|
||||
⎿ Found 0 lines
|
||||
|
||||
⏺ Let me search in the last_fm.ex file where this query might be generated:
|
||||
|
||||
⏺ Read(lib/last_fm.ex)
|
||||
⎿ Read 87 lines (ctrl+o to expand)
|
||||
|
||||
⏺ Let me search for more specific patterns to find where this query is generated:
|
||||
|
||||
⏺ Search(pattern: "purchased_at IS NOT NULL")
|
||||
⎿ Found 2 files (ctrl+o to expand)
|
||||
|
||||
⏺ Read(lib/music_library/collection.ex)
|
||||
⎿ Read 127 lines (ctrl+o to expand)
|
||||
|
||||
⏺ Search(pattern: "coalesce.*cover_hash")
|
||||
⎿ Found 1 file (ctrl+o to expand)
|
||||
|
||||
⏺ Read(lib/music_library/scrobble_activity.ex)
|
||||
⎿ Read 472 lines (ctrl+o to expand)
|
||||
|
||||
⏺ Found it! The query comes from the recent_activity/2 function in MusicLibrary.ScrobbleActivity. Let me examine the database
|
||||
indexes to understand the current optimization opportunities:
|
||||
|
||||
⏺ tidewave - execute_sql_query (MCP)(query: "SELECT name, sql FROM sqlite_master WHERE type='index' AND tbl_name IN
|
||||
('scrobbled_tracks', 'records') ORDER BY tbl_name, name")
|
||||
⎿ %Exqlite.Result{
|
||||
command: :execute,
|
||||
columns: ["name", "sql"],
|
||||
… +3 lines (ctrl+o to expand)
|
||||
|
||||
⏺ tidewave - execute_sql_query (MCP)(query: "SELECT name, sql FROM sqlite_master WHERE type='index' ORDER BY name")
|
||||
⎿ %Exqlite.Result{
|
||||
command: :execute,
|
||||
columns: ["name", "sql"],
|
||||
… +7 lines (ctrl+o to expand)
|
||||
|
||||
⏺ Let me check what indexes exist specifically for the tables we're working with:
|
||||
|
||||
⏺ tidewave - execute_sql_query (MCP)(query: "PRAGMA index_list('scrobbled_tracks')")
|
||||
⎿ %Exqlite.Result{
|
||||
command: :execute,
|
||||
columns: ["seq", "name", "unique", "origin", "partial"],
|
||||
… +3 lines (ctrl+o to expand)
|
||||
|
||||
⏺ tidewave - execute_sql_query (MCP)(query: "PRAGMA index_list('records')")
|
||||
⎿ %Exqlite.Result{
|
||||
command: :execute,
|
||||
columns: ["seq", "name", "unique", "origin", "partial"],
|
||||
… +3 lines (ctrl+o to expand)
|
||||
|
||||
⏺ tidewave - execute_sql_query (MCP)(query: "SELECT name FROM sqlite_master WHERE type='table' ORDER BY name")
|
||||
⎿ %Exqlite.Result{
|
||||
command: :execute,
|
||||
columns: ["name"],
|
||||
… +3 lines (ctrl+o to expand)
|
||||
|
||||
⏺ Let me check if the scrobbled_tracks table actually exists and examine its structure:
|
||||
|
||||
⏺ tidewave - execute_sql_query (MCP)(query: ".tables")
|
||||
⎿ Error: Failed to execute query: %Exqlite.Error{message: "near \".\": syntax error", statement: ".tables"}
|
||||
|
||||
⏺ Bash(mix ecto.migrate)
|
||||
⎿ 21:39:52.643 [info] Migrations already up
|
||||
|
||||
21:39:52.646 [debug] Exqlite: loading extension `/Users/cloud/github.com/cloud8421/music_library/_build/dev/lib/music_library
|
||||
… +5 lines (ctrl+o to expand)
|
||||
|
||||
|
||||
⏺ tidewave - execute_sql_query (MCP)(query: "SELECT name FROM sqlite_master WHERE type='table' AND name LIKE '%scrobbled%' OR name
|
||||
LIKE '%records%'")
|
||||
⎿ %Exqlite.Result{command: :execute, columns: ["name"], rows: [], num_rows: 0}
|
||||
|
||||
⏺ tidewave - execute_sql_query (MCP)(query: "SELECT name FROM sqlite_master WHERE type='table'", repo: "MusicLibrary.Repo")
|
||||
⎿ %Exqlite.Result{
|
||||
command: :execute,
|
||||
columns: ["name"],
|
||||
… +28 lines (ctrl+o to expand)
|
||||
|
||||
⏺ Now let me check the existing indexes:
|
||||
|
||||
⏺ tidewave - execute_sql_query (MCP)(query: "PRAGMA index_list('scrobbled_tracks')", repo: "MusicLibrary.Repo")
|
||||
⎿ %Exqlite.Result{
|
||||
command: :execute,
|
||||
columns: ["seq", "name", "unique", "origin", "partial"],
|
||||
… +3 lines (ctrl+o to expand)
|
||||
|
||||
⏺ tidewave - execute_sql_query (MCP)(query: "PRAGMA index_list('records')", repo: "MusicLibrary.Repo")
|
||||
⎿ %Exqlite.Result{
|
||||
command: :execute,
|
||||
columns: ["seq", "name", "unique", "origin", "partial"],
|
||||
… +18 lines (ctrl+o to expand)
|
||||
|
||||
⏺ tidewave - execute_sql_query (MCP)(query: "PRAGMA index_info('scrobbled_tracks_scrobbled_at_uts_title_index')", repo:
|
||||
"MusicLibrary.Repo")
|
||||
⎿ %Exqlite.Result{
|
||||
command: :execute,
|
||||
columns: ["seqno", "cid", "name"],
|
||||
… +3 lines (ctrl+o to expand)
|
||||
|
||||
⏺ tidewave - execute_sql_query (MCP)(query: "PRAGMA index_info('records_release_ids_index')", repo: "MusicLibrary.Repo")
|
||||
⎿ %Exqlite.Result{
|
||||
command: :execute,
|
||||
columns: ["seqno", "cid", "name"],
|
||||
… +3 lines (ctrl+o to expand)
|
||||
|
||||
⏺ Query Optimization Analysis
|
||||
|
||||
The query from MusicLibrary.ScrobbleActivity.recent_activity/2 has several optimization opportunities:
|
||||
|
||||
Current Issues:
|
||||
|
||||
1. Complex subqueries with json_each(): The query uses json_each() on release_ids arrays for both collection and wishlist joins,
|
||||
which is expensive for each row.
|
||||
2. Multiple LEFT JOINs with subqueries: Three separate subqueries are executed and joined, creating a cartesian product that's
|
||||
then filtered.
|
||||
3. JSON extraction in WHERE clauses: Using fragment("? ->> '$.musicbrainz_id'", t.album) requires JSON parsing for every row.
|
||||
4. Missing indexes: No composite indexes for the JSON-based join conditions.
|
||||
|
||||
Recommended Optimizations:
|
||||
|
||||
1. Add Strategic Indexes
|
||||
|
||||
-- Index for album musicbrainz_id JSON extraction (most critical)
|
||||
CREATE INDEX idx_scrobbled_tracks_album_mbid
|
||||
ON scrobbled_tracks((album ->> '$.musicbrainz_id'));
|
||||
|
||||
-- Composite index for the main query
|
||||
CREATE INDEX idx_scrobbled_tracks_scrobbled_at_album_mbid
|
||||
ON scrobbled_tracks(scrobbled_at_uts DESC, (album ->> '$.musicbrainz_id'));
|
||||
|
||||
2. Rewrite the Query Structure
|
||||
|
||||
Instead of multiple subqueries, use CTEs and reduce the number of joins:
|
||||
|
||||
def recent_activity_optimized(timezone, limit \\ 100) do
|
||||
# Single CTE for all releases with their collection/wishlist status
|
||||
releases_cte = """
|
||||
WITH releases AS (
|
||||
SELECT
|
||||
r.id as record_id,
|
||||
r.cover_hash,
|
||||
r.purchased_at IS NOT NULL as is_collected,
|
||||
sf.value as release_id
|
||||
FROM records r, json_each(r.release_ids) sf
|
||||
)
|
||||
"""
|
||||
|
||||
query = from t in Track,
|
||||
left_join: r in fragment("""
|
||||
(SELECT record_id, cover_hash, release_id,
|
||||
CASE WHEN is_collected THEN record_id END as collected_record_id,
|
||||
CASE WHEN NOT is_collected THEN record_id END as wishlisted_record_id
|
||||
FROM releases)
|
||||
"""),
|
||||
on: r.release_id == fragment("? ->> '$.musicbrainz_id'", t.album),
|
||||
left_join: ar in ArtistRecord,
|
||||
on: ar.record_id == r.record_id,
|
||||
order_by: [desc: t.scrobbled_at_uts],
|
||||
limit: ^limit,
|
||||
select: %{
|
||||
track: t,
|
||||
collected_record_id: r.collected_record_id,
|
||||
wishlisted_record_id: r.wishlisted_record_id,
|
||||
artist_id: ar.musicbrainz_id,
|
||||
cover_hash: r.cover_hash
|
||||
}
|
||||
end
|
||||
|
||||
3. Alternative: Materialized View Approach
|
||||
|
||||
Create a materialized view that pre-joins release data:
|
||||
|
||||
CREATE VIEW release_lookup AS
|
||||
SELECT
|
||||
r.id as record_id,
|
||||
r.cover_hash,
|
||||
r.purchased_at IS NOT NULL as is_collected,
|
||||
sf.value as release_id
|
||||
FROM records r, json_each(r.release_ids) sf;
|
||||
|
||||
CREATE INDEX idx_release_lookup_release_id ON release_lookup(release_id);
|
||||
|
||||
4. Denormalization Option
|
||||
|
||||
Consider adding a release_musicbrainz_id field directly to scrobbled_tracks to avoid JSON extraction:
|
||||
|
||||
# In migration
|
||||
add :album_musicbrainz_id, :string
|
||||
create index(:scrobbled_tracks, [:album_musicbrainz_id])
|
||||
create index(:scrobbled_tracks, [:scrobbled_at_uts, :album_musicbrainz_id])
|
||||
|
||||
⏺ Immediate Impact Recommendations:
|
||||
|
||||
High Impact, Low Risk:
|
||||
1. Add the JSON extraction index: CREATE INDEX idx_scrobbled_tracks_album_mbid ON scrobbled_tracks((album ->>
|
||||
'$.musicbrainz_id'))
|
||||
2. Add composite index: CREATE INDEX idx_scrobbled_tracks_scrobbled_at_album_mbid ON scrobbled_tracks(scrobbled_at_uts DESC,
|
||||
(album ->> '$.musicbrainz_id'))
|
||||
|
||||
Medium Impact, Medium Risk:
|
||||
3. Rewrite query to use a single CTE instead of multiple subqueries
|
||||
4. Create the release_lookup view for better join performance
|
||||
|
||||
High Impact, Higher Risk:
|
||||
5. Denormalize by adding album_musicbrainz_id column to eliminate JSON extraction entirely
|
||||
|
||||
The most critical optimization is adding indexes for the JSON extraction operations, which should provide immediate performance
|
||||
improvements with no code changes required.
|
||||
|
||||
|
||||
|
||||
|
||||
Reference in New Issue
Block a user