The Madlib website suggests it is compatible with Postgresql. Amazon Redhift is based on Postgresql. Can install Madlib on Redshift?
The Madlib library suggests it is compatible with postgres, but the full advantage of MADlib you will take when you will start using it with a MPP Database( Massively Parallel Database ) and also uses some internal pyhton libraries which are similar in both and which may not be the case in Amazon Redshift, it will be good if you use it with greenplum which is also an opensource now and is totally based on Postgres otherwise you will not be able to get the most out of it.