SQL uses a NOT EXISTS way, the result is difficult to perform very slowly.
Script is as follows:
select count(1) from (
SELECT /*+ full(t) */
t.*
FROM cpe_demands_t t
LEFT JOIN cpe_items_i_t i
ON t.demand_item = i.item_code
WHERE t.demand_id IS NOT NULL
AND t.batch_id = 51115 -- 入参
AND t.max_bom_level = 3 -- 入参
AND NOT EXISTS (SELECT /*+ parallel(kk, 10) */
1
FROM iscp_atp.cpe_pegging_t kk
WHERE kk.batch_id = 51115
AND kk.max_bom_level = 3
AND kk.demand_id = t.demand_id)
AND t.demand_date >= SYSDATE -7 * 7 -- 入参
AND t.demand_date < SYSDATE + 1 * 7 -- 入参
)LEFT JOIN instead of the way, performance significantly. The same amount of data, NOT EXISTS manner takes 422 seconds,
The LEFT JOIN way takes only 0.65 seconds, 649 times performance increase!
The optimized script is as follows:
select count(1) from (
select * from (
SELECT /*+ full(t) */
t.*
FROM cpe_demands_t t
LEFT JOIN cpe_items_i_t i
ON t.demand_item = i.item_code
WHERE t.demand_id IS NOT NULL
AND t.batch_id = 51115 -- 入参
AND t.max_bom_level = 3 -- 入参
AND t.demand_date >= SYSDATE -7 * 7 -- 入参
AND t.demand_date < SYSDATE + 1 * 7 -- 入参
) tt left join
cpe_pegging_t kk
on kk.demand_id = tt.demand_id
WHERE kk.demand_id is null
)Author: waylau