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Indexes to data in RAM are well-known and widely used. They are usually not called indexes, they are often called dictionaries, maps, hashmaps, associative arrays, or key-value stores. I am pretty sure you have heard of them. These data structures are useful for the same reason why disk-based indexes are useful for databases: to reduce the search time in a ...


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Is the purpose of the indexing data structures to address the limitations of disks? No. The purpose of using keys or indices with different types of data structures is to allow for O(1) access. The partitioning of data on disks and the organization of data into RAM are two vastly different subjects, though they have some crossover. If data is stored in RAM, ...


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Yes, indexes are still essential for in-ram data, as soon as you have a large amount of data and need to find a particular item by looking it up with a key (rather than via its address). It's basically the same reason why you need indexes for disk-based data, the main difference is that RAM access is much fast, especially random access (Harddisks are ...


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