我怀疑DB Engine正在多次调用Table-Valued-Function“GetUsageStatistic”,所以有一种方法来告诉引擎“GetUsageStatistic”是确定性的,应该只调用一次？

查询版本1

--Takes ~10 minutes
select *
from RosterLevel r
left join GetUsageStatistics( @mindate,@maxdate ) usage on r.UserID = usage.UserID;

查询版本2

--Takes ~10 seconds
select * into #usage from  GetUsageStatistics( @mindate,@maxdate );
select *
from RosterLevel r
left join #usage on r.UserID = #usage.UserID;