Question

我有两个表（PreOrder，PreOrderDetails），我想从中删除记录。这些表具有经典关系，其中详细信息表的外键引用预订表中的主键。 PreOrder拥有约1600万条记录，详细信息约为6000万条。

CREATE TABLE [dbo].[PreOrder](
    [PreOrderId] [uniqueidentifier] NOT NULL,
    -- more columns
 CONSTRAINT [PK_PreOrder] PRIMARY KEY NONCLUSTERED 
(
    [PreOrderId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, FILLFACTOR = 80) ON [PRIMARY]
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]

GO

ALTER TABLE [dbo].[PreOrder]  WITH CHECK ADD  CONSTRAINT [FK_PreOrder_PreOrder] FOREIGN KEY([PreOrderId])
REFERENCES [dbo].[PreOrder] ([PreOrderId])
GO

ALTER TABLE [dbo].[PreOrder] CHECK CONSTRAINT [FK_PreOrder_PreOrder]


CREATE TABLE [dbo].[PreOrderDetail](
    [PreOrderDetailId] [uniqueidentifier] NOT NULL,
    [PreOrderId] [uniqueidentifier] NOT NULL,
    more columns
 CONSTRAINT [PK_PreOrderDetail] PRIMARY KEY CLUSTERED 
(
    [PreOrderDetailId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, FILLFACTOR = 80) ON [PRIMARY]
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]

GO

ALTER TABLE [dbo].[PreOrderDetail]  WITH CHECK ADD  CONSTRAINT [FK_PreOrderDetail_PreOrder] FOREIGN KEY([PreOrderId])
REFERENCES [dbo].[PreOrder] ([PreOrderId])
GO

ALTER TABLE [dbo].[PreOrderDetail] CHECK CONSTRAINT [FK_PreOrderDetail_PreOrder]
GO

从预订中删除5条记录需要90秒，这太慢了。我猜它是因为约束，每次要删除一个preorderid时，都要检查完整的preorderdetails表。这个假设是否正确？

我可以做些什么来加快速度？现在记录的插入速度比删除它们的速度快。

Answer 1

是[PreOrderDetail]上没有索引。[PreOrderId]对插入很有用。
但基于列的选择和删除不会有好处您需要[PreOrderDetail]上的索引。[PreOrderId]

使用uniqueidentifier进行PK或索引效率不高，会迅速崩溃。

从具有约束的表中删除记录

1 个答案: