Sub-Join: Query Optimization Algorithm for Flash-Based Database *
Xiaofeng Meng · Jisuanji kexue yu tansuo · 2010
Compared with hard drive disk (HDD), solid state disk (SSD) has a lot of advantages, such as high ran- dom read performance, low power consumption and lightweight form. Therefore it is envisioned to be next genera- tion data storage instead of HDD. However, the enhancement of query performance for flash-based database is not the same as the I/O ratio of SSD to HDD. The reason is existing databases which are designed for HDD can not take full advantage of high I/O performance of SSD. A new join algorithm, Sub-Join, is proposed. Sub-Join firstly pro- jects the column of join and primary key as Sub-Table, and then executes join operations on Sub-Tables. Finally re- sults are gotten from original table according to the result of join on Sub-Tables. The compared experiments with Oracle Berkeley DB show Sub-Join outperforms original indexed nested-loop join at the ratio of about 40%~100%, which shows the high efficiency of this method.