QUERY PLAN
Aggregate (cost=19.42..19.43 rows=1 width=32)
-> Bitmap Heap Scan on tbl_sales_contract_invoices (cost=4.33..19.40 rows=6 width=6)
Recheck Cond: (contract_id = 4055)
-> Bitmap Index Scan on tbl_sales_contract_invoices_contract_id_idx (cost=0.00..4.33 rows=6 width=0)
Index Cond: (contract_id = 4055)