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

Question

我在使用一个经常使用的查询时遇到了一些性能问题。

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 是一个大表，每天都有数千条新记录，因此性能变得很糟糕。

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 表中检索数据并在结果为 null 时返回 0 吗？

谢谢你的想法，

克里斯蒂安

Answer 1

看起来你想要一个过滤聚合:

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;