Experiments showed that the sketch - based approaches could efficiently provide approximate answers for aggregate queries 合成數(shù)據(jù)的查詢實(shí)驗(yàn)表明草圖技術(shù)能有效地降低估算誤差。
Based on randomizing techniques , this paper discussed how the sketch - based approach estimates approximate answers to aggregate queries 摘要討論了基于草圖的復(fù)雜聚集查詢的近似處理算法。
Hierprefixcube retains advantages on computation and organization of prefixcube , and it can directly support aggregate queries on levels of the dimension hierarchy 它不僅保留了前綴立方在計(jì)算和組織結(jié)構(gòu)上的優(yōu)點(diǎn),又能直接和充分支持維層次級的聚集查詢。
In sigmod , philadelphia , pennsylvania , usa , 1999 , pp . 359 - 370 . 21 shanmugasundaram j , fayyad u , bradley p . compressed data cubes for olap aggregate query approximation on continuous dimensions 此外, pmc還能保證數(shù)據(jù)立方體中所有數(shù)據(jù)在查詢性能上的均衡性,這是傳統(tǒng)的視圖級別的部分物化所無法做到的。
Bo 5i is an intelligent integrated dss developing tool that aggregates query with analyzing report forms mainly based on on - line analytical process exploited by business intelligence corporation Businessobject ( bo )推出的智能決策支持系統(tǒng)工具bo5i是以olap技術(shù)為主體的、集查詢和分析報表為一體的決策支持系統(tǒng)開發(fā)工具。
According to the theory mentioned above , a new data stream management system jasper which extends the sql and forms a new continuous query language jaspercq is developed . jaspercq not only supports the continuous query , but also supplies the approximate query and predictive aggregate query 根據(jù)上述理論,開發(fā)了一個名為jasper的數(shù)據(jù)流管理原型系統(tǒng),對sql語言進(jìn)行了擴(kuò)充形成了可以支持連續(xù)查詢、近似查詢以及預(yù)測聚集查詢語義的流式查詢語言jaspercq 。
Second , the issue of approximate aggregation query on the data streams is discussed . meanwhile , the approximate query theories based on the histogram synopsis is proposed , and the autosuited histogram synopsis method and the histogram synopsis synchronization method are provided . third , the problem of predictive aggregate queries on the continuous data streams is researched , and a new predictive aggregate query method based on basic window synopsis and predictive equation is given 本文圍繞連續(xù)數(shù)據(jù)流上的聚集查詢展開討論,首先針對數(shù)據(jù)流上的精確聚集查詢問題,提出3種改進(jìn)的基于滑動窗口的精確聚集查詢算法,這三種算法可以在消耗很少內(nèi)存的情況下提供高效準(zhǔn)確的查詢結(jié)果;其次討論了連續(xù)數(shù)據(jù)流上的近似聚集查詢問題,給出了基于數(shù)據(jù)流滑動窗口的直方圖大綱理論,并提出了適用于滑動窗口的自適應(yīng)直方圖大綱生成算法和大綱同步策略;最后討論了連續(xù)數(shù)據(jù)流上的預(yù)測聚集查詢問題,提出了一種基于基本窗口及預(yù)測方程方法的預(yù)測聚集查詢算法。