feat(library): answer album completeness for a screenful in one query
A card grid has to know how much of an album is here — an album held 2 tracks of 10 wearing the same green tick as one held whole is the complaint the badge-accuracy work was filed about — and `GetAlbumCompleteness` is one query per album, which is fifty round trips for a grid of fifty. `GetAlbumsCompleteness` is the same question over a slice. It is two grouping levels rather than the single-album form's correlated subqueries, because a correlated subquery in the FROM clause is not something SQLite will reliably do, and because the slice may only be spelled once or sqlc expands it twice with independently numbered placeholders. An album with no files is absent from the result rather than zeroed: "I have none of this" and "I have no idea" are the third state `Known` exists to keep apart. The test that matters is that the two spellings never disagree — they are genuinely different SQL, so the risk is a drift in meaning (a disc's total counted once per file, a duplicate counted twice) rather than a typo.
This commit is contained in:
@@ -135,3 +135,49 @@ SELECT
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) AS INTEGER) AS known
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FROM audio_files a
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WHERE a.album_id = sqlc.arg(album_id);
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-- name: GetAlbumsCompleteness :many
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-- The same question as GetAlbumCompleteness, asked of a screenful of
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-- albums at once.
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--
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-- A card grid cannot afford one query per card, and the answer it wants
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-- is the one thing a badge cannot guess: an album held 9 tracks of 12
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-- must show the count, never a bare tick. So this is one query for the
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-- whole grid, asked only of the cards that have a local album id.
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--
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-- It is two grouping levels rather than the single-album form's
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-- correlated subqueries, because a correlated subquery in the FROM
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-- clause is not something SQLite will reliably do -- and because the
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-- slice may only be spelled once, or sqlc expands it twice with
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-- independently numbered placeholders.
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--
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-- The per-disc level is where the meaning is, and it is the same
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-- meaning as the single-album query. `owned` counts DISTINCT track
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-- numbers within a disc (this app detects duplicates, and counting two
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-- files of track 3 twice would report a short album as complete), with
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-- a file that declares no track number falling back to its own id
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-- because three untagged files are three tracks and not one.
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-- `expected` takes each disc's declared total and sums over discs,
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-- since a total is declared per disc and a release total written on
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-- every file of a two-disc album would double its expectation. A disc
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-- whose files declared nothing contributes a NULL that SUM ignores,
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-- and `known` is what says the album is therefore unanswerable.
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WITH per_disc AS (
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SELECT
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album_id AS album_id,
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COUNT(DISTINCT COALESCE(CAST(track_number AS TEXT), 'f' || id))
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AS owned_on_disc,
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MAX(total_tracks) AS disc_total,
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SUM(CASE WHEN total_tracks IS NULL THEN 1 ELSE 0 END)
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AS discs_without_a_total
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FROM audio_files
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WHERE album_id IN (sqlc.slice('album_ids'))
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GROUP BY album_id, COALESCE(disc_number, 1)
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)
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SELECT
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CAST(album_id AS INTEGER) AS album_id,
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CAST(SUM(owned_on_disc) AS INTEGER) AS owned,
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CAST(COALESCE(SUM(disc_total), 0) AS INTEGER) AS expected,
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CAST(SUM(discs_without_a_total) = 0 AS INTEGER) AS known
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FROM per_disc
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GROUP BY album_id;
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@@ -8,6 +8,7 @@ package sqlcgen
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import (
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"context"
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"database/sql"
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"strings"
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)
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const deleteAlbum = `-- name: DeleteAlbum :exec
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@@ -234,6 +235,98 @@ func (q *Queries) GetAlbumsByArtistName(ctx context.Context, arg GetAlbumsByArti
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return items, nil
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}
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const getAlbumsCompleteness = `-- name: GetAlbumsCompleteness :many
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WITH per_disc AS (
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SELECT
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album_id AS album_id,
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COUNT(DISTINCT COALESCE(CAST(track_number AS TEXT), 'f' || id))
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AS owned_on_disc,
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MAX(total_tracks) AS disc_total,
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SUM(CASE WHEN total_tracks IS NULL THEN 1 ELSE 0 END)
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AS discs_without_a_total
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FROM audio_files
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WHERE album_id IN (/*SLICE:album_ids*/?)
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GROUP BY album_id, COALESCE(disc_number, 1)
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)
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SELECT
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CAST(album_id AS INTEGER) AS album_id,
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CAST(SUM(owned_on_disc) AS INTEGER) AS owned,
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CAST(COALESCE(SUM(disc_total), 0) AS INTEGER) AS expected,
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CAST(SUM(discs_without_a_total) = 0 AS INTEGER) AS known
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FROM per_disc
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GROUP BY album_id
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`
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type GetAlbumsCompletenessRow struct {
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AlbumID int64
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Owned int64
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Expected int64
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Known int64
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}
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// The same question as GetAlbumCompleteness, asked of a screenful of
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// albums at once.
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//
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// A card grid cannot afford one query per card, and the answer it wants
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// is the one thing a badge cannot guess: an album held 9 tracks of 12
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// must show the count, never a bare tick. So this is one query for the
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// whole grid, asked only of the cards that have a local album id.
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//
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// It is two grouping levels rather than the single-album form's
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// correlated subqueries, because a correlated subquery in the FROM
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// clause is not something SQLite will reliably do -- and because the
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// slice may only be spelled once, or sqlc expands it twice with
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// independently numbered placeholders.
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//
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// The per-disc level is where the meaning is, and it is the same
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// meaning as the single-album query. `owned` counts DISTINCT track
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// numbers within a disc (this app detects duplicates, and counting two
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// files of track 3 twice would report a short album as complete), with
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// a file that declares no track number falling back to its own id
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// because three untagged files are three tracks and not one.
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// `expected` takes each disc's declared total and sums over discs,
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// since a total is declared per disc and a release total written on
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// every file of a two-disc album would double its expectation. A disc
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// whose files declared nothing contributes a NULL that SUM ignores,
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// and `known` is what says the album is therefore unanswerable.
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func (q *Queries) GetAlbumsCompleteness(ctx context.Context, albumIds []sql.NullInt64) ([]GetAlbumsCompletenessRow, error) {
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query := getAlbumsCompleteness
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var queryParams []interface{}
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if len(albumIds) > 0 {
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for _, v := range albumIds {
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queryParams = append(queryParams, v)
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}
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query = strings.Replace(query, "/*SLICE:album_ids*/?", strings.Repeat(",?", len(albumIds))[1:], 1)
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} else {
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query = strings.Replace(query, "/*SLICE:album_ids*/?", "NULL", 1)
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}
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rows, err := q.db.QueryContext(ctx, query, queryParams...)
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if err != nil {
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return nil, err
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}
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defer rows.Close()
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var items []GetAlbumsCompletenessRow
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for rows.Next() {
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var i GetAlbumsCompletenessRow
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if err := rows.Scan(
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&i.AlbumID,
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&i.Owned,
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&i.Expected,
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&i.Known,
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); err != nil {
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return nil, err
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}
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items = append(items, i)
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}
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if err := rows.Close(); err != nil {
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return nil, err
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}
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if err := rows.Err(); err != nil {
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return nil, err
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}
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return items, nil
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}
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const getAlbumsWithPendingReleaseMBID = `-- name: GetAlbumsWithPendingReleaseMBID :many
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SELECT id, pending_release_mbid FROM albums
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WHERE pending_release_mbid IS NOT NULL AND pending_release_mbid != ''
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