Why does snappy encodes the file ( increases the size ) instead of compressing it ?

[Praveenrajmani]

I tried compressing a dd generated file of bigger size using snappy.
And i found the resulting compressed size to be larger than the actual size.
How to avoid it ?
Is fixed size compression possible?

[creachadair]

Any compression algorithm that reduces the length of some strings will necessarily increase the length of others (intuitively, there are fewer possible codes of length n than strings of length n+1). Typically random-looking data will result in at least some expansion, since each literal will have some framing and Snappy doesn't use entropy coding.

I wouldn't expect more than a couple percent overhead even from a random file, but some expansion is possible.