3

我想根据此标准（返回 > 1 亿条记录）从 Table1 中删除记录（行 > 3 亿条记录）： Column1 IS NULL AND Column2 IS NULL AND Column3 IS NULL AND Column4 IS NULL AND Column5 IS NULL AND Column6 IS NULL AND Column7 IS NULL

表定义：

CREATE TABLE [dbo].[Table1](
    [ID] [uniqueidentifier] NOT NULL,
    [Column1] [float] NULL,
    [Column2] [float] NULL,
    [Column3] [float] NULL,
    [Column4] [float] NULL,
    [Column5] [float] NULL,
    [Column6] [float] NULL,
    [Column7] [float] NULL,
    [Table2ID] [uniqueidentifier] NULL, 
PRIMARY KEY CLUSTERED 
(
    [ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

注意：Table2ID 是来自 Table2 的外键约束

CREATE TABLE [dbo].[Table2](
    [ID] [uniqueidentifier] NOT NULL,
    [Column1] [date] NULL,
    [Column2] [tinyint] NULL,
    [Column3] [tinyint] NULL,
 CONSTRAINT [PK_Table2_ID] PRIMARY KEY CLUSTERED 
(
    [ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

我还想从 Table2 中删除所有在 Table1 中不再引用的孤立记录（行数约为 1000 万条记录）。以下是我采取的方法：

一个。使用 Table1ID 和 Table2ID 列创建临时表 #table1。捕获所有相关的 Table1ID 并运行以下删除查询。

Delete from Table1 where ID in (select Table1ID from #table1)

Delete from Table2 where ID in (select Table2ID from #table1)

上述查询可能由于表扫描而花费了大量时间。

湾。一切都与上面相同，但在 #table1 中的 Table1ID 列和 Table2ID 上创建唯一聚集索引并运行以下查询：

Delete from Table1 t1 join #table1 tmp1 on t1.ID=tmp1.Table1ID

Delete from Table2 t2 join #table1 tmp1 on t1.ID=tmp1.Table2ID

有没有更好的方法来处理这种情况？从 Table1 和 Table2 中删除记录的最佳方法是什么？

注意：我知道我们创建一个新表、转储所有相关数据并重命名它的方法。请提供有关替代方法的建议 - 利弊。

4

2 回答 2

4

由于您确实想删除高百分比，因此您可以考虑这种方法

 SELECT col1, col2, ... INTO #SomeHoldingtable
            FROM MyTable WHERE ..condition..

 TRUNCATE TABLE MyTable

 INSERT MyTable (col1, col2, ...)
           SELECT col1, col2, ... FROM #SomeHoldingtable
于 2013-07-08T10:35:20.507 回答
0

如果我理解正确，过滤索引和批量删除应该会有所帮助（SQL Server 2008 或更高版本）：

create index IX_1 on dbo.Table1 (Column1, Column2, ...) include (Table2ID) where Column1 is NULL and Column2 is NULL and ...

create table #Deleted (Table2ID uniqueidentifier NULL)
create index #IX_Deleted on #Deleted (Table2ID) where Table2ID is not NULL


select 1
while @@rowcount > 0
    delete top (50000) T
    output deleted.Table2ID into #Deleted (Table2ID)
    from dbo.Table1 T
    where Column1 is NULL and Column2 is NULL and ...

select 1
while @@rowcount > 0
    delete top (50000) T
    from dbo.Table2 T
        join (select distinct Table2ID from #Deleted where Table2ID is not NULL) D on D.Table2ID = T.ID

drop table #Deleted
drop index IX_1 on dbo.Table1

并且，根据需要（一次操作，或定期），IX_1可以保留索引。

在 SQL Server 2005 上，可以对索引计算列执行相同的操作。

于 2013-07-08T14:17:15.107 回答