public static final String SQL_SELECT_DUPLICATE_LABELS = "SELECT l1.* " +
            "FROM LABEL l1, LABEL l2 " +
            "WHERE l1.LABELID <> l2.LABELID " +
            "   AND (l1.NAME = l2.NAME OR (l1.NAME IS NULL AND l2.NAME IS NULL)) " +
            "   AND (l1.OWNER = l2.OWNER OR (l1.OWNER IS NULL AND l2.OWNER IS NULL)) " +
            "   AND (l1.NAMESPACE = l2.NAMESPACE OR (l1.NAMESPACE IS NULL AND l2.NAMESPACE IS NULL)) " +
            "ORDER BY l1.NAME, l1.OWNER, l1.NAMESPACE, l1.LABELID ASC";

Nested Loop  (cost=1001.35..73786.65 rows=159723919 width=71) (actual time=20.236..304665.775 rows=324 loops=1)
  ->  Gather Merge  (cost=1001.06..18070.10 rows=88091 width=71) (actual time=20.143..620.023 rows=88168 loops=1)
        Workers Planned: 1
        Workers Launched: 1
        ->  Incremental Sort  (cost=1.05..7159.85 rows=51818 width=71) (actual time=0.874..397.286 rows=44084 loops=2)
"              Sort Key: l1.name, l1.owner, l1.namespace, l1.labelid"
              Presorted Key: l1.name
              Full-sort Groups: 105  Sort Method: quicksort  Average Memory: 27kB  Peak Memory: 27kB
"              Pre-sorted Groups: 14  Sort Methods: quicksort, external merge  Average Memory: 23kB  Peak Memory: 25kB  Average Disk: 241kB  Peak Disk: 3384kB"
              Worker 0:  Full-sort Groups: 542  Sort Method: quicksort  Average Memory: 28kB  Peak Memory: 28kB
"                Pre-sorted Groups: 17  Sort Methods: quicksort, external merge  Average Memory: 23kB  Peak Memory: 25kB  Average Disk: 120kB  Peak Disk: 2048kB"
              ->  Parallel Index Scan using l_name_idx on label l1  (cost=0.29..5026.71 rows=51818 width=71) (actual time=0.040..7.619 rows=44084 loops=2)
  ->  Index Scan using l_name_idx on label l2  (cost=0.29..0.62 rows=1 width=55) (actual time=3.445..3.448 rows=0 loops=88168)
        Index Cond: ((name)::text = (l1.name)::text)
        Filter: ((l1.labelid <> labelid) AND (((l1.owner)::text = (owner)::text) OR ((l1.owner IS NULL) AND (owner IS NULL))) AND ((l1.namespace)::text = (namespace)::text))
        Rows Removed by Filter: 51714
Planning Time: 3.087 ms
Execution Time: 304666.246 ms

SELECT l1.*
FROM label l1
JOIN label l2
  ON l1.name = l2.name
 AND l1.owner = l2.owner
 AND l1.namespace = l2.namespace
 AND l1.labelid <> l2.labelid
UNION ALL
SELECT l1.*
FROM label l1
JOIN label l2
  ON l1.name = l2.name
 AND l1.owner IS NULL
 AND l2.owner IS NULL
 AND l1.namespace = l2.namespace
 AND l1.labelid <> l2.labelid
ORDER BY name, owner, namespace, labelid;

Gather Merge  (cost=31598083.15..50527758.37 rows=161522001 width=71) (actual time=91.720..93.302 rows=324 loops=1)
  Workers Planned: 2
  Workers Launched: 2
  ->  Sort  (cost=31597083.13..31883111.67 rows=114411417 width=71) (actual time=83.133..83.137 rows=108 loops=3)
"        Sort Key: l1.name, l1.owner, l1.namespace, l1.labelid"
        Sort Method: quicksort  Memory: 25kB
        Worker 0:  Sort Method: quicksort  Memory: 70kB
        Worker 1:  Sort Method: quicksort  Memory: 25kB
        ->  Parallel Append  (cost=0.29..2205342.37 rows=114411417 width=71) (actual time=41.869..82.713 rows=108 loops=3)
              ->  Parallel Hash Join  (cost=2966.26..6933.39 rows=14827 width=71) (actual time=28.958..50.164 rows=320 loops=1)
                    Hash Cond: (((l1.name)::text = (l2.name)::text) AND ((l1.owner)::text = (l2.owner)::text) AND ((l1.namespace)::text = (l2.namespace)::text))
                    Join Filter: (l1.labelid <> l2.labelid)
                    Rows Removed by Join Filter: 67527
                    ->  Parallel Seq Scan on label l1  (cost=0.00..1551.64 rows=51864 width=71) (actual time=0.003..2.940 rows=88168 loops=1)
                    ->  Parallel Hash  (cost=1551.64..1551.64 rows=51864 width=55) (actual time=28.532..28.532 rows=88168 loops=1)
                          Buckets: 131072  Batches: 1  Memory Usage: 6848kB
                          ->  Parallel Seq Scan on label l2  (cost=0.00..1551.64 rows=51864 width=55) (actual time=0.008..11.059 rows=88168 loops=1)
              ->  Nested Loop  (cost=0.29..11131.89 rows=94998115 width=71) (actual time=41.911..65.984 rows=1 loops=3)
                    ->  Parallel Seq Scan on label l1_1  (cost=0.00..1551.64 rows=12238 width=71) (actual time=0.017..1.705 rows=6880 loops=3)
                          Filter: (owner IS NULL)
                          Rows Removed by Filter: 22509
                    ->  Index Scan using l_name_idx on label l2_1  (cost=0.29..0.77 rows=1 width=22) (actual time=0.009..0.009 rows=0 loops=20641)
                          Index Cond: ((name)::text = (l1_1.name)::text)
                          Filter: ((owner IS NULL) AND (l1_1.labelid <> labelid) AND ((l1_1.namespace)::text = (namespace)::text))
                          Rows Removed by Filter: 4
Planning Time: 1.089 ms
Execution Time: 93.398 ms