use IN and JOIN instead of NOT IN and simple subselect

[butonic]

The background job keeps burning CPU cycles on my poor ATOM board...

Before:

# EXPLAIN DELETE FROM "oc_music_tracks" WHERE "file_id" NOT IN (SELECT "fileid" FROM "oc_filecache");
                                      QUERY PLAN                                       
---------------------------------------------------------------------------------------
 Delete on oc_music_tracks  (cost=0.00..33871909.50 rows=13900 width=6)
   ->  Seq Scan on oc_music_tracks  (cost=0.00..33871909.50 rows=13900 width=6)
         Filter: (NOT (SubPlan 1))
         SubPlan 1
           ->  Materialize  (cost=0.00..2331.24 rows=42216 width=4)
                 ->  Seq Scan on oc_filecache  (cost=0.00..1955.16 rows=42216 width=4)

after

# EXPLAIN DELETE FROM "oc_music_tracks" WHERE "file_id" IN (SELECT "file_id" FROM "oc_music_tracks" LEFT JOIN "oc_filecache" ON "file_id"="fileid" WHERE "fileid" IS NULL);
                                                 QUERY PLAN                                                  
-------------------------------------------------------------------------------------------------------------
 Delete on oc_music_tracks  (cost=4010.11..4018.41 rows=1 width=18)
   ->  Nested Loop  (cost=4010.11..4018.41 rows=1 width=18)
         ->  HashAggregate  (cost=4010.11..4010.12 rows=1 width=16)
               ->  Hash Anti Join  (cost=2689.86..4010.11 rows=1 width=16)
                     Hash Cond: (public.oc_music_tracks.file_id = oc_filecache.fileid)
                     ->  Seq Scan on oc_music_tracks  (cost=0.00..598.00 rows=27800 width=10)
                     ->  Hash  (cost=1955.16..1955.16 rows=42216 width=10)
                           ->  Seq Scan on oc_filecache  (cost=0.00..1955.16 rows=42216 width=10)
         ->  Index Scan using music_tracks_file_id_idx on oc_music_tracks  (cost=0.00..8.27 rows=1 width=10)
               Index Cond: (file_id = public.oc_music_tracks.file_id)

@MorrisJobke ping me if you want me to explain the SQL changes. I left the other three deletes as an exercise for you ... and because I need to sleep to get better.

ref #90

[scrutinizer-notifier]

The inspection completed: No new issues

[MorrisJobke]

👍

[ghost]

@butonic
Could it be possible that this also fix #289 ?

[butonic]

It avoids the subselects, so I'd say yes, but I am pretty tired and might be wrong...

[ghost]

Thanks for the follow-up. 👍 Will have a look after the changes here was included in the next version of the app.