Examples of indexing techniques b trees hashbased

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Unformatted text preview:   <k, rid of data record with search key value k> –  <k, list of rids of data records with search key k> •  Choice of alterna6ve for data entries is orthogonal to the indexing technique used to locate data entries with a given key value k. –  Examples of indexing techniques: B+ trees, hash ­based structures –  Typically, index contains auxiliary informa6on that directs searches to the desired data entries Alterna6ves for Data Entries (Contd.) •  Alterna6ve 1: –  If this is used, index structure is a file organiza6on for data records (instead of an unordered heap file or sorted file). –  At most one index on a given collec6on of data records can use Alterna6ve 1. (Otherwise, data records are duplicated, leading to redundant storage and poten6al inconsistency.) –  If data records are very large, # of pages containing data entries is high. Implies size of auxiliary informa6on in the index is also large, typically. Alterna6ves for Data Entries (Contd.) •  Alterna6ves 2 and 3: –  Data entries typically much smaller than data r...
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