hive - Can i concurrently set MAPJOIN hint and STREAMTABLE hint? -
can use this?
select /*+ mapjoin(t2)*//*+ streamtable(t1)*/ t1.c1. t2.c1 t1 left outer join t2 on t1.c1 = t2.c1;
and confuse "streamtable" on different join keys.
for example: t3 biggest table,and t2 secondary big table,t1 smallest table.
select /*+ streamtable(t2)*/ t1.c3, t2.c2, t3.c3 t2 left outer join t1 on t2.c1=t1.c1 left outer join t3 on t2.c2=t3.c2;
so if when t2 join t1 it's ok.but when t2 join t3,if t2 if still treated big table? how can handle situation?
you can achieve following:
select /*+ mapjoin(t2), streamtable(t1)*/ t1.c1. t2.c1 t1 left outer join t2 on t1.c1 = t2.c1;
there non-trivial number of cbo-related defects might still run into, involving windowing functions , columnar formats in experience. therefore useful know how apply hints.
Comments
Post a Comment