组合索引字段顺序引发的死锁问题

组合主键、聚集索引引发的死锁问题，还是索引字段顺序、选择性的问题，切记。

-- SPID: 61
exec sp_executesql N'DELETE FROM SYLOCKAID WHERE MKID=@param0 AND DATACAT=@param1 AND DATAID=@param2',N'@param0 varchar(max) ,@param1 varchar(max) ,@param2 varchar(max) ',@param0='JCSF',@param1='JZSF_TD_YSZXZJB',@param2='201504cbb52e-9cfb-46d1-b2dd-c18a54f2db8501'

-- SPID: 69
exec sp_executesql N'DELETE FROM SYLOCKAID WHERE MKID=@param0 AND DATACAT=@param1 AND DATAID=@param2',N'@param0 varchar(max) ,@param1 varchar(max) ,@param2 varchar(max) ',@param0='JCSF',@param1='JZSF_TD_YSZXZJB',@param2='201502aa91d5-12e3-40b1-acd1-9c63109a36bc01'

sp_helpindex sylockaid;

index_name      index_description                                    index_keys
PK_SYLOCKAID    clustered, unique, primary key located on PRIMARY    MKID, DATACAT, DATAID

-- 调整索引字段顺序后，问题解决
alter table sylockaid 
    drop constraint PK_SYLOCKAID;

alter table sylockaid
    add constraint PK_SYLOCKAID primary key clustered(DATAID, MKID, DATACAT);