Any best tool to migrate one database to another

My requirement is to migrate database from DB2 to Postgres. The objects that i need to migrate is tables, sps, functions.

I tried some tools but not getting satisfactory output. Please suggest the best. It would be best if its an open source.

Thanks in advance.

one idea is to try premium tools

another idea is to do it by = plugins = !! available .. could be visual studio or in db2 itself
or in PostGres itself ..

another idea it to use Scripting !!! and if necessary converting !!! Tools or manually

Please google search .. Tons and Tons of stuff there !!