In a major expansion, Yahoo Inc. said Monday that its online search engine index now spans more than 20 billion Web documents and images, nearly double the material scanned by rival Google Inc.

Yahoo's expansion doesn't necessarily mean it produces more useful results than Google, which has long been considered the Internet's most comprehensive database.

But the breakthrough gives the Sunnyvale-based company the bragging rights to a widely watched measurement for assessing the power of an Internet search engine.

Yahoo said its index, boosted by a recent upgrade, covers 20.5 billion online "objects," comprised of about 19 billion documents and 1.5 billion images.

That's a hell of a lot of web content.