swh-dedup=# select count(*) from chunk tablesample system (0.0003) left join chunked_content_chunk on chunk_id = chunk.id;
 count 
-------
  4181
(1 row)

Time: 728.211 ms
swh-dedup=# select count(*) from chunk tablesample system (0.001) left join chunked_content_chunk on chunk_id = chunk.id;

 count 
-------
 14505
(1 row)

Time: 652203.960 ms (10:52.204)