公开(公告)号：US06421664B1

公开(公告)日：2002-07-16

申请号：US09334543

申请日：1999-06-16

申请人： Micahel John Groeschel ,  Scott Dennis Helt ,  Rebecca Nan Brady Legler

发明人： Micahel John Groeschel ,  Scott Dennis Helt ,  Rebecca Nan Brady Legler

IPC分类号： G06F1730

CPC分类号： G06F17/30327 ,  G06F17/30469 ,  Y10S707/99932 ,  Y10S707/99933 ,  Y10S707/99942

摘要： An apparatus, program product and method for estimating the number of keys within an index key range over an index using page pointers to pages in the index comprises a program configured for scanning the index, from a divergence point of the key range, until a page pointer is found and incrementing a counter for each found page pointer. The program is further configured for determining if the page pointer points to a leaf page in the index, and if it does, continuing the scan to find the next page pointer without going to the corresponding leaf page. Otherwise, the program continues the scan to find the next page pointer and continues the scan for page pointers and increments the counter until the index is scanned for the entire key range. Upon completion of the scan, the program determines an estimate of the number of keys utilizing the counter.

摘要翻译： 一种用于使用索引中的页面的页面指针来估计在索引上的索引关键字范围内的键的数量的装置，程序产品和方法，包括被配置用于从所述键范围的发散点扫描所述索引直到页面 找到指针并递增每个找到的页面指针的计数器。 该程序还被配置用于确定页面指针是否指向索引中的叶子页面，并且如果是，继续扫描以找到下一页面指针而不去相应的叶子页面。 否则，程序继续扫描以找到下一页指针，并继续扫描页面指针，并递增计数器，直到索引扫描整个键范围。 扫描完成后，程序确定使用计数器的键数量的估计。