Hi Boris, > Also, when they say tablets - I assume this is before replication? so in > reality, it is number of nodes x cpu cores / replication factor? If this is > the case, it is not looking good...
No, I think this is post-replication. The underlying assumption is that you want to maximize parallelism for large tables, and since Impala only uses one read thread per tablet, that means ensuring the number of tablets is close or equal to the overall number of cores. However, during a scan Impala will choose one of the tablet's replicas to read from, so you don't need to "reserve" a core for the other replicas. >> can someone clarify if this recommendation below - does it mean physical or >> hyper-threaded CPU cores? quite a big difference... I think this refers to hyper-threaded CPU cores (i.e. a CPU unit capable of executing an OS thread). But I'd be curious to hear if your workload is substantially more or less performant either way.
