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公开(公告)号：US5903888A
公开(公告)日：1999-05-11
申请号：US808096
申请日：1997-02-28
IPC分类号： G06F17/30
CPC分类号： G06F17/30324 , G06F17/30327 , G06F17/30463 , G06F17/30492 , Y10S707/99932 , Y10S707/99933 , Y10S707/99934 , Y10S707/99942 , Y10S707/99943 , Y10S707/99944
摘要： A method and apparatus for processing a query combines the use of different index types to minimize the rows of data that need to be retrieved from a table. A first index is accessed based on a query to produce a first result having a first format, for example a bitmap index outputting a bitmap. A second index, for example a B-tree index, is also accessed based on the query to produce a second result having a second format, for example a sequence of rowids. The first result is converted to a converted result having the second format, and the converted result and the second result are combined to obtain an end result. The end result can then be used to locate data that satisfies the query while minimizing the rows of data that need to be retrieved from a table during the query processing.
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公开(公告)号：US5884307A
公开(公告)日：1999-03-16
申请号：US808585
申请日：1997-02-28
IPC分类号： G06F17/30
CPC分类号： G06F17/30312 , Y10S707/99931 , Y10S707/99933 , Y10S707/99935 , Y10S707/99937 , Y10S707/99943
摘要： A method and apparatus for updating a segmented bitmapped index to reflect a change made to data upon which the segmented index is based. Change records specifying changes to bitmap segments contained in the segmented bitmapped index are sorted by key value (bitmap segment) and row ID (bit) before being applied to the segmented bitmapped index. When the change records are being applied to the bitmap segment contained in the segmented bitmapped index, the index entry containing the bitmap segment to be updated is locked. If a new bitmap segment must be generated, the index entry covering a row in the data having a row ID less than the row ID of the change is first locked. Then a new index entry is generated, stored in the segmented bitmapped index, and the locked index entry unlocked. If the segmented bitmapped index does not contain an index entry covering a row in the data having a row ID less than the row ID of the change, then a dummy index entry is generated, stored in the segmented bitmapped index, and locked. A new index entry is then generated and stored in the segmented bitmapped index, after which the dummy index entry is unlocked and deleted.
摘要翻译： 一种用于更新分段位图索引以反映对分段索引所依据的数据所做的改变的方法和装置。 包含在分段位图索引中的位图段的更改的更改记录在应用于分段位图索引之前按键值（位图段）和行ID（位）进行排序。 当更改记录被应用于包含在分段位图索引中的位图片段时，包含要更新的位图片段的索引条目被锁定。 如果必须生成新的位图段，则首先锁定具有小于更改行ID的行ID的数据中包含行的索引条目。 然后生成新的索引条目，存储在分段位图索引中，并锁定索引条目。 如果分段位图索引不包含覆盖具有小于该变化的行ID的行ID的数据中的行的索引条目，则生成虚拟索引条目，存储在分段位图索引中并被锁定。 然后生成新的索引条目并将其存储在分段位图索引中，之后解锁和删除虚拟索引条目。
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公开(公告)号：US5822748A
公开(公告)日：1998-10-13
申请号：US808097
申请日：1997-02-28
IPC分类号： G06F17/30
CPC分类号： G06F17/30454 , Y10S707/99931 , Y10S707/99932 , Y10S707/99933 , Y10S707/99934 , Y10S707/99935 , Y10S707/99936 , Y10S707/99937 , Y10S707/99953
摘要： Sort plus operations such as "group by" and "distinct" generally require sorting of the retrieved data before performing the sort plus operation. A method and apparatus is disclosed for executing a query specifying a sort plus operation without performing the sorting operation. A cost-based optimizer determines at least one execution path where the data is retrieved from a sorted source and the data is processed to satisfy the query without sorting. Execution costs are determined for the respective execution paths, and the execution path having the lowest overall execution cost is selected to process the query.
摘要翻译： 分组加操作，例如“分组”和“不同”通常需要在执行排序加运算之前对检索的数据进行排序。 公开了一种用于在不执行排序操作的情况下执行指定排序加操作的查询的方法和装置。 基于成本的优化器确定至少一个执行路径，其中从排序的源检索数据，并且处理数据以满足查询而不进行排序。 对于各个执行路径确定执行成本，并且选择具有最低总执行成本的执行路径来处理该查询。
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