You shouldn't be seeing this error. I think you are probably hitting an old bug where sometimes an invalid execution plan was generated. - https://issues.apache.org/jira/browse/IMPALA-5689 or https://issues.apache.org/jira/browse/IMPALA-3063   It should be fixed in CDH5.13.0 or later. ... View more

So IDLE_SESSION_TIMEOUT doesn't actually do anything if you set it in impala-shell. There's a technical distinction here - "set" in impala-shell is implemented in the shell itself, then send along with the queries. Whereas if you run "set" as a statement through, say, the JDBC driver, then "set" is run as a server-side command that modifies the session state.   I tried to reproduce the issue on my local Impala environment, but couldn't. I was watching the /sessions page in the debug page and I could see the "last accessed" time get continually incremented while the query was in the queue. I think any timeout issue probably got indirectly fixed by https://issues.apache.org/jira/browse/IMPALA-5216 in CDH6.1/Impala 3.1, since the query state would be polled directly by impala-shell while the query is in the queue, rather than having impala-shell blocked waiting for a response.   Thanks for submitting the support request, that should help get to the bottom of this. ... View more

We have made some changes to decimal type resolution behaviour in recent versions. Most of them are controlled by the DECIMAL_V2 option and the default was changed starting in Impala 3.0.   The best way forward is to report a bug in the Impala issue tracker - https://cwiki.apache.org/confluence/display/IMPALA/Contributing+to+Impala with the steps required to reproduce the symptoms you see. Then it can be tracked and triaged properly. This forum is not great for doing that. ... View more

I see what you're saying there. The different from Hive isn't deliberate, but I believe this only happens in the very special case when all of the values in the CASE are NULL, without any cast. If any of them have a type, the query will execute. E.g. the below query runs and returns NULL.   select 1 * (CASE WHEN '1' IS NULL THEN NULL ELSE cast(NULL as integer) END); Interestingly postgres behaves the same way as Impala   psql (9.5.17, server 9.4.8) Type "help" for help. postgres=# select 1 * (CASE WHEN '1' IS NULL THEN NULL ELSE NULL END); ERROR: operator does not exist: integer * text LINE 1: select 1 * (CASE WHEN '1' IS NULL THEN NULL ELSE NULL END); ^ HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts. postgres=# select 1 * (NULL); ?column? ---------- (1 row) postgres=# select 1 * (NULL); ?column? ---------- (1 row)   We could probably file a bug if this is causing issues for you, there no specific reason it shouldn't work that I know of. ... View more

Sessions with queries that are queued in admission control generally shouldn't be considered be considered idle. What Impala server version are you connected to? What does your script look like? Are you running 300+ instances of impala-shell at the same time? ... View more

The output of "explain <query>" is often helpful too. ... View more