REPLICA_PREFERENCE Query Option (Impala 2.7 or higher only)
REPLICA_PREFERENCE query option
lets you spread the load more evenly if hotspots and bottlenecks persist, by allowing hosts to do local reads,
or even remote reads, to retrieve the data for cached blocks if Impala can determine that it would be
too expensive to do all such processing on a particular host.
Type: numeric (0, 3, 5)
or corresponding mnemonic strings (
The gaps in the numeric sequence are to accomodate other intermediate
values that might be added in the future.
Default: 0 (equivalent to
Added in: Impala 2.7.0