ANALYZE FORMAT=JSON Examples

Example #1

Customers who have ordered more than 1M goods.

ANALYZE FORMAT=JSON
SELECT CONT(*)
FROM customer
WHERE
  (SELECT SUM(o_totalprice) FROM orders WHERE o_custkey=c_custkey) > 1000*1000;

The query takes 40 seconds over cold cache

EXPLAIN: { "query_block": { "select_id": 1, "r_loops": 1, "r_total_time_ms": 39872, "table": { "table_name": "customer", "access_type": "index", "key": "i_c_nationkey", "key_length": "5", "used_key_parts": ["c_nationkey"], "r_loops": 1, "rows": 150303, "r_rows": 150000, "r_total_time_ms": 270.3, "filtered": 100, "r_filtered": 60.691, "attached_condition": "((subquery#2) > <cache>((1000 * 1000)))", "using_index": true }, "subqueries": [ { "query_block": { "select_id": 2, "r_loops": 150000, "r_total_time_ms": 39531, "table": { "table_name": "orders", "access_type": "ref", "possible_keys": ["i_o_custkey"], "key": "i_o_custkey", "key_length": "5", "used_key_parts": ["o_custkey"], "ref": ["dbt3sf1.customer.c_custkey"], "r_loops": 150000, "rows": 7, "r_rows": 10, "r_total_time_ms": 39208, "filtered": 100, "r_filtered": 100 } } } ] } }

ANALYZE shows that 39.2 seconds were spent in the subquery, which was executed 150K times (for every row of outer table).

Comments

Comments loading...
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.