Impala memory constraints (and the errors that accompany them)

I saw this sort of error come up when using Impala:

When I execute some aggregation query, a red bar comes up that indicates some failures but doesn’t really tell me much at all. I hit “execute” again on the same query, usually the below sort of error comes up in the Query Log and the query fails.

“impala Backend 3:Memory Limit Exceeded Process: memory limit exceeded. Limit=”

In my case the query memory usage was somewhere just above 8GB and the limit was right around 8GB. Well, this means the configured memory limit for Impala queries was reached on at least one node. Yeah, if just one node dies, then the entire thing dies. In my case, there was just one Impala group that was set to around an 8GB memory limit for Impala.

Here’s how to check and change:

Cloudera Manager > Home > Impala in desired Cluster > Configuration > ”

Impala Daemon Memory Limit” > make those as big as you can > restart cluster.