发明名称 |
Method, system, and program for reverse index scanning |
摘要 |
Provided is a system, method, and program for performing a reverse scan of an index implemented as a tree of pages. Each leaf page includes one or more ordered index keys and previous and next pointers to the previous and next pages, respectively. The scan is searching for keys in the leaf pages that satisfy the search criteria. If a current index key is a first key on a current page, then a request is made for a conditional shared latch on a previous page prior to the current page. If the requested conditional shared latch is not granted, then the latch on the current page is released and a request is made for unconditional latches on the previous page and the current page. After receiving the latches on the previous and current pages, a determination is made of whether the current index key is on the current page if the current page was modified since the unconditional latch was requested. The current index key is located on the current page if the current index key is on the current page. A determination is then made of whether the located current index key satisfies the search criteria.
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申请公布号 |
US2002078047(A1) |
申请公布日期 |
2002.06.20 |
申请号 |
US20000736608 |
申请日期 |
2000.12.14 |
申请人 |
INTERNATIONAL BUSINESS MACHINES CORPORATION |
发明人 |
HOLLINES ROBERT J.;LEE CHRISTINA MARIE;LEVISH DAVID L.;SHADDUCK MICHAEL R.;WANG YUFEN |
分类号 |
G06F17/30;(IPC1-7):G06F17/30 |
主分类号 |
G06F17/30 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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