Auto explain de la requête

Query Text: UPDATE cc_files SET is_scheduled = false WHERE is_scheduled = true AND id NOT IN ( SELECT s.file_id FROM cc_schedule AS s LEFT JOIN cc_show_instances AS i ON s.instance_id = i.id WHERE s.ends > now() at time zone 'UTC'AND i.ends > now() at time zone 'UTC' );
        Update on public.cc_files  (cost=4.60..1132.12 rows=1 width=11647)
          ->  Seq Scan on public.cc_files  (cost=4.60..1132.12 rows=1 width=11647)
                Output: cc_files.id, cc_files.name, cc_files.mime, cc_files.ftype, cc_files.directory, cc_files.filepath, cc_files.state, cc_files.currentlyaccessing, cc_files.editedby, cc_files.mtime, cc_files.utime, cc_files.lptime, cc_files.md5, cc_files.track_title, cc_files.artist_name, cc_files.bit_rate, cc_files.sample_rate, cc_files.format, cc_files.length, cc_files.album_title, cc_files.genre, cc_files.comments, cc_files.year, cc_files.track_number, cc_files.channels, cc_files.url, cc_files.bpm, cc_files.rating, cc_files.encoded_by, cc_files.disc_number, cc_files.mood, cc_files.label, cc_files.composer, cc_files.encoder, cc_files.checksum, cc_files.lyrics, cc_files.orchestra, cc_files.conductor, cc_files.lyricist, cc_files.original_lyricist, cc_files.radio_station_name, cc_files.info_url, cc_files.artist_url, cc_files.audio_source_url, cc_files.radio_station_url, cc_files.buy_this_url, cc_files.isrc_number, cc_files.catalog_number, cc_files.original_artist, cc_files.copyright, cc_files.report_datetime, cc_files.report_location, cc_files.report_organization, cc_files.subject, cc_files.contributor, cc_files.language, cc_files.file_exists, cc_files.soundcloud_id, cc_files.soundcloud_error_code, cc_files.soundcloud_error_msg, cc_files.soundcloud_link_to_file, cc_files.soundcloud_upload_time, cc_files.replay_gain, cc_files.owner_id, cc_files.cuein, cc_files.cueout, cc_files.silan_check, cc_files.hidden, false, cc_files.is_playlist, cc_files.ctid
                Filter: (cc_files.is_scheduled AND (NOT (hashed SubPlan 1)))
                SubPlan 1
                  ->  Nested Loop  (cost=0.00..4.60 rows=1 width=4)
                        Output: s.file_id
                        Join Filter: (s.instance_id = i.id)
                        ->  Seq Scan on public.cc_schedule s  (cost=0.00..3.45 rows=1 width=8)
                              Output: s.id, s.starts, s.ends, s.file_id, s.stream_id, s.clip_length, s.fade_in, s.fade_out, s.cue_in, s.cue_out, s.media_item_played, s.instance_id, s.playout_status, s.broadcasted, s."position"
                              Filter: (s.ends > timezone('UTC'::text, now()))
                        ->  Seq Scan on public.cc_show_instances i  (cost=0.00..1.12 rows=2 width=4)
                              Output: i.id, i.starts, i.ends, i.show_id, i.record, i.rebroadcast, i.instance_id, i.file_id, i.time_filled, i.created, i.last_scheduled, i.modified_instance
                              Filter: (i.ends > timezone('UTC'::text, now()))