QUERY PLAN
Aggregate (cost=8.18..8.19 rows=1 width=4)
-> Index Only Scan using idx_tbl_ledger_auxiliary_items_ledger_serial_no on tbl_ledger_auxiliary_items (cost=0.14..8.16 rows=1 width=28)
Index Cond: ((ledger_id = 1) AND (type = '1'::smallint))