A spatial index for hybrid storage.

The introduction of flash SSDs has accelerated the performance of DBMSes. However, the intrinsic characteristics of flash motivated many researchers to investigate new efficient data structures. The emergence of 3DXPoint, a new non-volatile memory, sets new challenges: 3DXPoint features low latency and high IOPS even at small queue depths. However, the cost of 3DXPoint is 4 times higher than that of a flash-based device, rendering hybrid storage systems a good alternative. In this paper we pursue exploiting the efficiency of both 3DXPoint and flash-based devices introducing H-Grid, a variant of Grid-File for hybrid storage. H-Grid uses a flash SSD as main store and a small 3DXPoint device to persist the hottest data. The performance of the proposed index is experimentally evaluated, comparing it against GFFM, a flash efficient implementation of Grid File. The results show that H-Grid is faster than GFFM execution on a flash SSD, reducing the single point search time from 35% up to 43%.