BATCH_SIZE Query Option
Number of rows evaluated at a time by SQL operators. Unspecified or a size of 0 uses a predefined default size. Using a large number improves responsiveness, especially for scan operations, at the cost of a higher memory footprint.
This option is primarily for testing during Impala development, or for use under the direction of the appropriate support channel.
Default: 0 (meaning the predefined default of 1024)
Range: 0-65536. The value of 0 still has the special meaning of "use the default", so the effective range is 1-65536. The maximum applies in Impala 2.11 and higher.