可以使用DolphinDB的repartitionDS函数满足上述需求，具体例子如下：
ds = repartitionDS(query=<select DateTime,SecurityID from loadTable("dfs://SH_TSDB_snapshot_MultiColumn", "snapshot") where date(DateTime) in 2021.12.01 2021.12.06 2021.12.07, SecurityID in `600021`603659>, column=`SecurityID, partitionScheme=`a`b)
def disctcode(t){
r1 = select distinct(date(DateTime)) as date from t
r2 = select distinct(SecurityID) as SecurityID from t
return r1,r2
}
timer{
a1,a2=mr(ds, disctcode, ,)
b1 = unionAll(a1,0,0)
b2 = unionAll(a2,0,0)
}