Regarding Oracle - Oracle distribution and verification I would recommend to use GoldenGate and Veridata Oracle GoldenGate</title><meta name="Title" content="Oracle GoldenGate"><meta name=&q…
Unfortunately GG does not support Informix directly - but maybe using JDBC adapter works.
Best would be to post your issue in their community: GoldenGate
SQLines Data tool can migrate and validate data when you migrate from Informix to Oracle. You can easily compare row count as well as content. The tool orders rows by primary or unique keys/indexes, or if they are not available by all columns (except LOBs).