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Compressed bitmaps in C#
branch: master


latest commit a7e7e81807
@lemire authored


(c) 2012 Kemal Erdogan, Daniel Lemire and Ciaran Jessup,
This code is licensed under the Apache
License, Version 2.0 (ASL2.0)

This is a compressed variant of
the standard bitarray class. It uses a 64-bit RLE-like
compression scheme. It can be used to implement
bitmap indexes.

The goal of word-aligned compression is not to 
achieve the best compression, but rather to 
improve query processing time. Hence, we try
to save CPU cycles, maybe at the expense of
storage. However, the EWAH scheme we implemented
is always more efficient storage-wise than an
uncompressed bitarray. 

For more details regarding the compressed format, see Section 3
of the following paper:

Daniel Lemire, Owen Kaser, Kamel Aouiche, Sorting improves word-aligned bitmap indexes.
 Data & Knowledge Engineering 69 (1), pages 3-28, 2010.
(The PDF file is freely available on the arXiv site.)

== Unit testing ==

 Building using Mono

You can build CSharpEWAH using the open source
Mono toolchain using the xbuild command.
Just type xbuild in the main directory. This
should build a C# executable file that you
will then find in a newly created bin 

$ xbuild

Then you can run the executable using
the mono command:

$ mono ./EWAH.RunTests/bin/Debug/EWAH.RunTests.exe

This will run unit tests.

=== Usage ==

See example.cs.

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