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From Michael Zalewski <zalew...@optonline.net>
Subject RE: HDF
Date Wed, 28 May 2003 01:25:26 GMT
> We thought that it would be better on memory if we kept the structures
> compressed until needed.  So a Section object would not be uncompressed
> until it was needed by the programmer. So the only uncompressed objects
> the ones the programmer has made direct calls on. Then, when a setter was
> called on a Section object it would create a compressed sprm (if needed)
> the SEPX. There is a memory-cpu trade off. Who knows, we may change our
> minds if it turns out to be real slow. We are trying to avoid an object
> model that is a total memory pig.

I have been working for some time now on a library to access Microsoft
files. I use the same technique of not unpacking the structure until it is
accessed by the getter method. From my limited experience, any performance
price you pay is more than overwhelmed by the file I/O and by POIFS (the
Ole Structured File System).

And I think for large documents on small machines (small in POI terms means
less than 1 GB of memory it seems), I think the technique is actually faster
unless you can back up all the memory used by POI with real memory.

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