const MIGRATION_020: &str = r#"
CREATE INDEX IF NOT EXISTS idx_items_season ON items(season_id);
"#;Expand description
Migration to index items.season_id.
Episodes link to their season via season_id (parent_id is NULL in the
cache). The container-rollup queries used by the Downloaded browse and the
disk-usage aggregation join children.season_id = c.id, which without this
index degrades to an unindexable scan — a large synced catalog then makes
the Downloaded page hang (“Loading your downloads…”). parent_id,
album_id, and series_id were already indexed; this closes the gap.