fix(users/Profpatsch/whatcd-resolver): speed up table query

This took a while to figure out, but essentially sorting a thing with
one million queries takes a long time, as compared to doing it on a
small subset of things and then joining against the final ordering.

The generated column helps, too.

Change-Id: I1bf283e2be060748eebda92576e3d062c51a6777
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11681
Autosubmit: Profpatsch <mail@profpatsch.de>
Tested-by: BuildkiteCI
Reviewed-by: Profpatsch <mail@profpatsch.de>

users/Profpatsch/whatcd-resolver/src/Redacted.hs

@@ -400,34 +400,30 @@ getBestTorrents ::
 getBestTorrents opts = do
   queryWith
     [sql|
-      SELECT
+      WITH filtered_torrents AS (
-        group_id,
+        SELECT DISTINCT ON (torrent_group)
-        torrent_id,
+          id
-        seeding_weight,
+        FROM
-        torrent_json,
+          redacted.torrents
-        torrent_group_json,
-        has_torrent_file,
-        transmission_torrent_hash
-      FROM (
-        SELECT DISTINCT ON (tg.group_id)
-          tg.group_id,
-          t.torrent_id,
-          seeding_weight,
-          t.full_json_result AS torrent_json,
-          tg.full_json_result AS torrent_group_json,
-          t.torrent_file IS NOT NULL as has_torrent_file,
-          t.transmission_torrent_hash,
-          (jsonb_path_query_array(t.full_json_result, '$.artists[*].id')) as torrent_artists
-        FROM redacted.torrents t
-        JOIN redacted.torrent_groups tg ON tg.id = t.torrent_group
-        ORDER BY tg.group_id, seeding_weight DESC
-      ) as _
         WHERE
           -- onlyDownloaded
-        ((NOT ?::bool) OR has_torrent_file)
+          ((NOT ?::bool) OR torrent_file IS NOT NULL)
           -- filter by artist id
           AND
-        (?::bool OR (to_jsonb(?::int) <@ torrent_artists))
+          (?::bool OR (to_jsonb(?::int) <@ (jsonb_path_query_array(full_json_result, '$.artists[*].id'))))
+        ORDER BY torrent_group, seeding_weight DESC
+      )
+      SELECT
+        tg.group_id,
+        t.torrent_id,
+        t.seeding_weight,
+        t.full_json_result AS torrent_json,
+        tg.full_json_result AS torrent_group_json,
+        t.torrent_file IS NOT NULL AS has_torrent_file,
+        t.transmission_torrent_hash
+      FROM filtered_torrents f
+      JOIN redacted.torrents t ON t.id = f.id
+      JOIN redacted.torrent_groups tg ON tg.id = t.torrent_group
       ORDER BY seeding_weight DESC
     |]
     ( do