Got it.
Thanks for your reply.
Zhiwen Sun
On Wed, Dec 23, 2015 at 2:24 PM, Gopal Vijayaraghavan
wrote:
>
> > But why disable mapjoin has better performance when we don't use cast to
> >string(user always lazy)?
> >
> > Join key values comparison in in reduce stage is more quickly?
>
> The Ha
> But why disable mapjoin has better performance when we don't use cast to
>string(user always lazy)?
>
> Join key values comparison in in reduce stage is more quickly?
The HashMap is slower than the full-sort +
sorted-merge-join.
It shouldn't be, but it hits the worst-case performance for th
Thanks to Gopal.
But why disable mapjoin has better performance when we don't use cast to
string(user always lazy)?
Join key values comparison in in reduce stage is more quickly?
Zhiwen Sun
p;9456
On Wed, Dec 23, 2015 at 2:36 AM, Gopal Vijayaraghavan
wrote:
>
> > We found that when we join
> We found that when we join on two different type keys , hive will
>convert all join key to Double.
This is because of type coercions for BaseCompare, so that String:Integer
comparisons with "<=" will work similarly to "=".
> b.id to double. When the conversion occurs, map join will become very
Hi all:
We found that when we join on two different type keys , hive will convert
all join key to Double.
Consider such simple query:
explain
> select *
> from table_a a
> join table_b b on a.id = b.id
>
If type of a.id is int while b.id 's type is string, hive will convert a.id
and b.id to dou
