06-29-2016 08:50 PM
Is there a way to use something like Oracle's "IGNORE NULLS" with the last_value() analytic function (or similar)? I want to fill all the nulls in a column with the last value in that column that was non-null. In Oracle I can do something like the below. How can I implement this in Impala? I need to forward fill the null values if possible, and if the partition begins with null, I'd like to backfill from the first non-null value.
-- Oracle sample query --
select user, date, val,
case when val is null
then last_value(val ignore nulls)
over (partition by user order by date)
end as new_val
06-30-2016 08:53 AM
I think we already have an open issue for this that is being actively worked on https://issues.cloudera.org/browse/IMPALA-3210
I.e. we don't support it yet but it's in the pipeline.