IMPALA: RIGHT OUTER JOIN type with no equi-join predicates can only be executed with a single node

Question

I have enable stats using `COMPUTE STATS` on a table. After this when I re-run the query, it's giving me an error `A RIGHT OUTER JOIN type with no equi-join predicates can only be executed with a single node plan`. Dropping the stats is execuring the query. I'm trying to improve the query performance.

sgrip · Accepted Answer

By default, Impala uses something called as a “broadcast join” which assumes that the left table is larger than the right. Which is not true in my case.

It does the join inversion inherently if this is not done in the query.

When such an inversion is to be overridden, it is suggested to be overriden by the keyword “STRAIGHT_JOIN“.

Or re-write the query to swap the join sets and make the left join a right join.

Since in this case it’s non-equi join, right outer joins do not support a right outer join in Impala yet. Replaced the left join with an INNER JOIN and swapping the datasets.

sgrip · Answer

Note: My query has a left join and doesn’t have a right join.

Select f1, f2, f3 from ( Select t.t1, t.t2, t.t3 from table1 t Left join Select p.p1, p.p2, p.p3 from table2 p on p.p1=t.t1)i Where condition

Sign up

Please use your Cloudera account.

Login to the community

Please use your Cloudera account.