Patent ID: 8200645
Filing Date: 2012-06-12
Classification: G06F

Abstract:
1. A method for performing concurrent scans of stored data based upon an index data structure for the stored data, the method comprising: performing a first scan of stored data, the first scan sequentially scanning through an index data structure indexing the stored data and retrieving, into a buffer, records contained within the stored data in a sequence defined by the index structure, each entry of the index structure indicating a respective record in the stored data; maintaining, over a duration of the first scan, a first scan current scan location within the index data structure, the first scan current scan location indicating a currently accessed record within the stored data structure for the first scan; accepting a request for a second scan of the stored data, the second scan specifying a second start key and a second end key within the index data structure; estimating, while performing the first scan, a sharing potential between the first scan and the second scan, the sharing potential indicating a likelihood that execution of the second scan accesses records contained within the buffer due to the performing the first scan; determining, while performing the first scan and based on the sharing potential, a starting index scan location within the index data structure for the second scan, the staring location index scan location of the second scan being located relative to the first scan current scan location to cause the second scan to read records stored within the buffer due to the performing the first scan; starting the second scan at the starting index scan location and proceeding to the second end key; and providing results of the first scan and the second scan.