Flash数据管理 Zhou da 2007-9-9

Tape is Dead Disk is Tape Flash is Disk Jim Gray Microsoft December 2006

应用范围 物理特性

Flash disk is a popular storage medium for digital device

Flash disk develops at a high speed

The market Oracle Berkeley DB (non SQL) Oracle Database Lite 10g (SQL) Sybase SQL Anywhere - SQL Database Software, Embedded Database IBM DB2 Everyplace Microsoft SQL Server 2005 Compact Edition

Tape is Dead Disk is Tape Flash is Disk Jim Gray Microsoft December 2006

Cooperation INRIA(法国国家信息与自动化研究所)

Flash硬盘结构

磁盘结构

The advantage of flash disk Higher of speed of read and write. About the 300 times and 50 times of that of the hard disk. Smaller size Less power consumption Data can been preserved longer Shock resistance Picture1 Flash disk Picture2 Magnetic disk

Difference between flash disk and magnetic disk Read/Write/Erase Asymmetric speed of read/write/erase Erase before rewrite Limited erase times Read/write page, erase block, 1 block=64 pages Read/Write The same speed of read/write Rewrite in-place No limited write times Read/write byte Note: one flash page contains 2048 bytes

数据管理研究带来的问题------ Wandering trees

索引相关工作 Sang-Won Lee 尹少宜 Sigmod 2007

索引相关工作 Related work Remain work: Sang-Won Lee: leaf nodes in the B+ tree Shaoyi yin: index the primary key Remain work: Secondary key index

数据管理研究带来的问题------事务处理 Related work Transaction on the log file system Recovery One of the signature features of database systems is that they provide transactions and guarantee that in the event of a crash, the system can be brought back to a consistent state. We intend to explore new mechanisms for storing recovery information to achieve higher performance on flash memory. ------ MIT Research Abstracts - 2007

数据管理研究带来的问题------查询优化 磁盘的查询优化需要尽量避免对分散的数据的读取，从而建立了主索引和大量副索引。 Flash硬盘上相当于可以建立任意多的主索引，所以索引性能会得到极大的提高

数据管理研究带来的问题------并行计算

数据管理研究带来的问题------并行计算

数据管理研究带来的问题------混合式系统 Hybrid flash/magnetic systems. Magnetic disk will continue to have a lower cost per byte than flash memory for the foreseeable future. We plan to investigate methods for automatically migrating portions of database from magnetic disk to flash memory to boost performance in systems where the database can not be economically stored entirely on flash memory.

Flash数据管理 谢 谢 