联合索引建立依据

区分度高的放在前面

select count(distinct destinationmachine) cdd, count(distinct factoryname) cdf, count(distinct requesttype) cdr, count(distinct CASSETTETYPE) cdc, count(distinct state) cds from dsptransfercommand;

CDD CDF CDR CDC CDS---------- --------- ---------- ---------- ----------259 4 4 2 8
Select count(*) from dsptransfercommand表计算总数

选择索引选择性好的列放在前面。