3rd February 2009, 1 min read

Compressed bitmaps in Java

A bitmap is an efficient array of boolean values. They are commonly used in bitmap indexes. The Java language has a bitmap class: BitSet.

Unfortunately, the Java BitSet class will not scale to large sparse bitmaps—the Sun implementation does not use compression.

I published a new free alternative: JavaEWAH.

References:

• The library contains the 64-bit EWAH algorithm described—among other places—in one of my recent research papers.
• It is a Java port of some of my C++ Bitmap Index library.

Credit:

• Glen Newton gave me the idea for this project.