Space-efficient Relative Error Order Sketch over Data Streams

We consider the problem of continuously maintaining order sketches over data streams with a relative rank error guarantee . Novel space-efficient and one-scan randomised techniques are developed. Our first randomised algorithm can guarantee such a relative error precision with confidence 1 - using O( 1 2 log 1 log 2 N) space, where N is the number of data elements seen so far in a data stream. Then, a new one-scan space compression technique is developed. Combined with the first randomised algorithm, the one-scan space compression technique yields another one-scan randomised algorithm that guarantees the space requirement is O(1 log(1 log 1 )log2+ N 1-1/2 ) (for > 0) on average while the worst case space remains O( 1 2 log 1 log 2 N). These results are immediately applicable to approximately computing quantiles over data streams with a relative error guarantee and significantly improve the previous best space bound O( 1 3 log 1 log N). Our extensive experiment results demonstrate ...

• Type: Conference
• Year: 2006
• Where: ICDE
• Authors: Ying Zhang, Xuemin Lin, Jian Xu, Flip Korn, Wei Wang 0011
• Keywords: Database, ICDE 2006, One-scan Randomised Algorithm, Relative Error Guarantee, Space Compression Technique