data from a file instead of memory

I am sure there is a simple answer to this, but I sure can't find it. I have found myself practicly writing a database, but its all in memory.

I am using MSVC 6 MFC template class CMap. It works great, does what I need and its fast. However, my dataset is large, say 20MB or so and I don't want to clog up the memory.

I store the data on disk, but when I serialize in my CMap it sucks the whole file into memory.

Is there a way to get the benefits of CMap functionality with the data being accessed directly from the file?

Look up on MSDN for Memory Mapped Files.....

Quote:

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File Mapping Functions
The following functions are used with file mapping.



CreateFileMapping
FlushViewOfFile
MapViewOfFile
MapViewOfFileEx
MapViewOfFileVlm
OpenFileMapping
UnmapViewOfFile
UnmapViewOfFileVlm

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With them you can create a map of a peart of a big file, work on it, close the mapping (dont get confused withthe map you are using as a data struct ;)) and that segment will be saved to disk

Thanks. That looks like it may do the trick. I'll let you know.

Thanks for the info, but I found a different way to go. Use a database file without a database.

http://www.codeguru.com/mfc_database/daoarticle.html

File-mapping is a good solution for most I/O, especially when working with large file size.

Kuphryn

That's a good link