3.6. Indexing
An index is a table or a data structure, which is maintained to determine the location of rows (records) in a file that satisfy some condition. The index table has entry consisting of value of the key attribute for a particular record and the pointer to the location where the record is stored. Thus, each index entry corresponds to a data record on the secondary storage (disk) device. A record is retrieved from the disk first by searching the index for the address of the record in the index table and then reading the record from this address. Fig. 3.19 (b) illustrates the example of maintaining index tables, for example, master index, cylinder index, track index and so on. A library catalogue system by author-wise or title-wise ...
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