I am working on file indexing and successful in indexing and retrieving the records. But If file is too big having millions of records then it takes time to read the index file. Is there any way that index is stored in memory and when i run my program i can use that map?

Manish

What index are you talking about?
If it is the data within your file I'm afraid you are going to have to be more specific as we have no idea what file you are working with.
A file can be indexed by seeking to a position within it. Google file seek operations and choose results pertinent to your platform.

If you are concerned about how long it takes to read a file with millions of entries and want to load that into memory consider that in order to do that you
1) Have to have enough memory to support the size of the file you are dealing with
2) Will have to load the entire contents into the memory region anyway

If you are only reading this one time then there is no benefit to memory mapping due to #2. If the file is too large for your memory then you will see limited benefit as you likely spend a large amount of time being paged in and out of memory.

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