DigestJoin: Exploiting Fast Random Reads for Flash-Based Joins

13 years 11 months ago

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Abstract—Flash disks have been an emerging secondary storage media. In particular, there have been portable devices, multimedia players and laptop computers that are conﬁgured with no magnetic disks but ﬂash disks. It is envisioned that some RDBMSs will operate on ﬂash disks in the near future. However, the I/O characteristics of ﬂash disks are different from those of magnetic disks. Thus, in this paper, we study the core of query processing in RDBMSs — join processing — on ﬂash disks. Speciﬁcally, we propose a new join method, called DigestJoin, to exploit fast random reads of ﬂash disks. DigestJoin consists of two phases: (1) projecting the join attributes followed by a join on the projected attributes; and (2) fetching the full tuples that satisfy the join to produce the ﬁnal join results. While the problem of tuple/page fetching with minimum I/O cost (in the second phase) is intractable, we propose three heuristic fetching strategies. We have implemented Diges...

Yu Li, Sai Tung On, Jianliang Xu, Byron Choi, Haib

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