Impala Broken in 5.20


(Andrew Poland) #1

We are discovering that after upgrading from Looker 5.8.5 to 5.20.26 (LTS) we are no longer able to perform any queries to Impala. All queries fail with the following error message:

The Cloudera Impala with Native Driver database encountered an error while running this query.
[Simba]JDBC A ResultSet was expected but not generated from query "-- Query Context ‘{“user_id”:34,“history_id”:103244}’

Looking at the Impala query logs, I see a fundamental difference between queries produced by the 5.8 and 5.20 versions of looker. The 5.20 versions have a new comment section at the top of the query like so:

– Query Context ‘{“user_id”:34,“history_id”:103236}’ select * from attribution_models limit 100

The query with the comment fails to execute on Impala presumably because there is no line break between the comment and the start of the query. This comment is not present in queries generated by looker 5.8.

The root cause appears to be the “Context Comments” feature that was an optional Labs feature in 5.8 but appears is no longer optional in 5.20. If we turn this feature on in 5.8 we can reproduce the error.

I have two questions:

  1. Is there a way to turn off Context Comments in Looker 5.20 so we can work around this? As far as we can tell this option is no longer on the labs screen and we no longer have control over it.

  2. What is Looker’s official stance on support for Apache Impala? I’m concerned that if a bug this obvious makes it into the LTS release that has been out for months, I’m wondering if anyone at Looker did even the most basic testing on the Impala support before this went out the door?


(Morgan Imel) #2

Hi Andrew,

No, it’s not possible to turn off context comments in Looker 5.20. Could you please email (or hop on chat) so that we can help get this fixed for you ASAP?



(Andrew Poland) #3

Hi Morgan,

We spoke to Spencer on chat yesterday who was going to bring this up with engineering but I don’t believe we’ve heard back yet. Right now our stage environment is completely unusable.


(Morgan Imel) #4

Ok, thanks for letting us know! I’ll track that down and make sure that we get back to you on that thread shortly.


(Morgan Imel) #5

Hey Andrew, wanted to close the loop here!
This issue was specific to the driver that was being used and has been resolved on our end by our engineering team.

To address your question about dialect testing; we do thoroughly test supported dialects (like Impala) with the drivers that are packaged with the Looker product. At the moment we don’t have tests set up for the specific driver that you have, but this is something we’re looking into.