Error: cannot execute site query. select 
  tbl_datasets.method_id as dataset_method, 
  COALESCE(
    tbl_analysis_entity_prep_methods.method_id :: text, 
    '0' :: text
  ) as prep_method, 
  count(*) 
from 
  tbl_analysis_entities 
  left join tbl_analysis_entity_prep_methods on tbl_analysis_entity_prep_methods.analysis_entity_id = tbl_analysis_entities.analysis_entity_id 
  join tbl_datasets on tbl_analysis_entities.dataset_id = tbl_datasets.dataset_id 
where 
  tbl_datasets.method_id is not null 
group by 
  dataset_method, 
  prep_method 
order by 
  dataset_method