1. A computer-implemented method, comprising: determining that a database query warrants a first projection operation to project a plurality of input rows to a plurality of projected rows, wherein each of the plurality of input rows has one or more variable-length columns; constructing, by a computer processor, a first projection control block to describe the first projection operation; offloading the first projection operation to a hardware accelerator; and providing the first projection control block to the hardware accelerator, wherein the first projection control block enables the hardware accelerator to perform the first projection operation at streaming rate.