Question

使用Rails和Postgres。

我有3张桌子（我们称它们为“制造商”，“直升机”和“船”）。制造商模型与has_many关联到直升机（通过“ manufacturer_helicopters”表和模型），与has_many关联到Boats（通过“ manufacturer_boats”表和模型）。

在显示页面上，我应该呈现与直升机（具有“ helicopter_ids”之一）或与船（具有“ boat_ids”之一）连接的唯一制造商。

此外，“直升机”关联具有更高的优先级，因此，我们应仅过滤那些拥有“直升机”且具有给定的直升飞机ID或完全没有“直升机”的制造商。

这是我想出的查询，但它确实很慢-只需几秒钟即可查询（每个表几乎有100万条记录）

result = Manufacturer.distinct(:id)
                     .left_outer_joins(:manufacturer_helicopters, :manufacturer_boats)
                     .where('helicopter_id IN (?) OR boat_id IN (?)', helicopter_ids, boat_ids)
result.where('manufacturer_helicopters.helicopter_id = ? OR manufacturer_helicopters.helicopter_id IS NULL', helicopter_id)

我非常感谢任何有关提高性能的建议。

编辑这是解释

 Unique  (cost=104750.30..115799.60 rows=184155 width=384)
   ->  Sort  (cost=104750.30..105210.69 rows=184155 width=384)
         Sort Key: manufacturer.id, manufacturer.full_name, manufacturer.serial_number, manufacturer.contact_email, manufacturer.pending, manufacturer.created_at, manufacturer.updated_at, manufacturer.in_production, manufacturer.in_planning, manufacturer.web_url, manufacturer.mobile_url, manufacturer.country, manufacturer.city, manufacturer.zip_code, manufacturer.logo, manufacturer.street, manufacturer.address, manufacturer.last_manufactured_at, manufacturer.archived, manufacturer.external_manufacturer_id, manufacturer.external_serial_number, manufacturer.distributor_id, manufacturer.visible
         ->  Merge Left Join  (cost=1.35..24441.43 rows=184155 width=384)
               Merge Cond: (manufacturer.id = manufacturer_helicopter.helicopter_id)
               Filter: ((manufacturer_helicopter.helicopter_id = 4) OR (manufacturer_boat.boat_id = 1))
               ->  Merge Left Join  (cost=1.06..19442.76 rows=260211 width=388)
                     Merge Cond: (manufacturer.id = manufacturer_boat.boat_id)
                     ->  Index Scan using manufacturer_pkey on manufacturers  (cost=0.42..11437.12 rows=260211 width=384)
                     ->  Index Scan using manufacturer_on_boat_id_boat on manufacturer_boat  (cost=0.42..5352.52 rows=160207 width=8)
               ->  Index Scan using index_manufacturer_helicopter_on_helicopter_id on manufacturer_helicopter  (cost=0.29..3343.37 rows=100005 width=8)

Answer 1

maker.id是否已索引？您的maker_pk是什么？

如何解决慢速非重复查询

1 个答案: