Firebird SQL：由于合并或可以重写查询速度慢

Question

我在使用常用查询时遇到一些性能问题。

SELECT
v.id,
coalesce((SELECT sum(amount) FROM artjournal WHERE variant_ref=v.id AND storage_ref=1 AND atype_ref in (1,3,4)), 0) "fv", 
coalesce((SELECT sum(amount) FROM artjournal WHERE variant_ref=v.id AND storage_ref=1 AND atype_ref=2), 0) "ivo", 
coalesce((SELECT sum(amount) FROM artjournal WHERE variant_ref=v.id AND storage_ref=1 AND atype_ref=5), 0) "iio", 
coalesce((SELECT sum(amount * mvalue) FROM artjournal WHERE variant_ref=v.id AND storage_ref=1), 0) "vw"
FROM productvariant v

由于 artjournal 很大 table 并且每天都有数千条新记录，因此性能越来越差。

我在所有 ID 字段上都有索引。

有没有办法重写这个语句来加快速度？或者我可以使用不同的方式从 artjournal table 和 return 中检索数据 0 如果结果为空？

感谢您的想法，

克里斯蒂安

Answer 1

您似乎需要过滤聚合：

SELECT v.id,
       sum(case when a.atype_ref in (1,3,4) then a.amount else 0 end) as "fv",
       sum(case when a.atype_ref = 2 then a.amount else 0 end) as "ivo",
       sum(case when a.atype_ref = 5 then a.amount else 0 end) as "iio",
       sum(a.amount * a.mvalue) as "vw"
FROM productvariant v
  LEFT JOIN artjournal a ON a.variant_ref = v.id
WHERE storage_ref = 1
GROUP BY v.id;

Firebird SQL：由于合并或可以重写查询速度慢

Firebird SQL: query slow due to coalesce or can it be rewritten

sql

firebird

coalesce