检查重复项时最好的自联接技术

Question

我正在尝试优化生产中需要很长时间的查询.目标是根据匹配的字段值条件查找重复记录,然后删除它们.当前查询通过t1.col1 = t2.col1上的内连接使用自连接,然后使用where子句检查值.

select * from table t1 
inner join table t2 on t1.col1 = t2.col1
where t1.col2 = t2.col2 ...

什么是更好的方法来做到这一点？或者根据索引是否完全相同？也许

select * from table t1, table t2
where t1.col1 = t2.col1, t2.col2 = t2.col2 ...

这个表有100米+行.

MS SQL,SQL Server 2008 Enterprise

select distinct t2.id
    from table1 t1 with (nolock)
    inner join table1 t2 with (nolock) on  t1.ckid=t2.ckid
    left join table2 t3 on t1.cid = t3.cid and t1.typeid = t3.typeid
    where 
    t2.id > @Max_id and
    t2.timestamp > t1.timestamp and
    t2.rid = 2 and
    isnull(t1.col1,'') = isnull(t2.col1,'') and 
    isnull(t1.cid,-1) = isnull(t2.cid,-1) and
    isnull(t1.rid,-1) = isnull(t2.rid,-1)and 
    isnull(t1.typeid,-1) = isnull(t2.typeid,-1) and
    isnull(t1.cktypeid,-1) = isnull(t2.cktypeid,-1) and
    isnull(t1.oid,'') = isnull(t2.oid,'') and
    isnull(t1.stypeid,-1) = isnull(t2.stypeid,-1)  

    and (
            (
                t3.uniqueoid = 1
            )
            or
            (
                t3.uniqueoid is null and 
                isnull(t1.col1,'') = isnull(t2.col1,'') and 
                isnull(t1.col2,'') = isnull(t2.col2,'') and
                isnull(t1.rdid,-1) = isnull(t2.rdid,-1) and 
                isnull(t1.stid,-1) = isnull(t2.stid,-1) and
                isnull(t1.huaid,-1) = isnull(t2.huaid,-1) and
                isnull(t1.lpid,-1) = isnull(t2.lpid,-1) and
                isnull(t1.col3,-1) = isnull(t2.col3,-1) 
            )
    )

Answer 1

为什么自我加入:这是一个综合问题.

希望你有col1,col2,...的索引

--DELETE table
--WHERE KeyCol NOT IN (
select
    MIN(KeyCol) AS RowToKeep,
    col1, col2, 
from
    table
GROUP BY
    col12, col2
HAVING
   COUNT(*) > 1
--)

但是,这需要一些时间.有一个看看批量删除技术