Your first step should be to read all the "Behavior Changes" portions of the 4 major "What's new" sections in the Help that apply to you, starting with SQL Anywhere 11 - Changes and Upgrading » What's new in version 10.0.0
In DCX (DocCommentXchange), the same material starts at http://dcx.sybase.com/1101en/sachanges_en11/newjasper.html
That will tell you what to look for. Your own knowledge of your application should tell you where to look. If you don't have a thorough understanding of ALL the code in your application (which is OK, especially if you didn't write all of it yourself) then reviewing ALL of the schema and ALL of the application code is probably required.
Don't forget the triggers... and events and web services (CREATE SERVICE)... if you use any of those... especially triggers, folks often forget they exist.
answered 10 Nov '09, 07:26
One disrupting change I stumbled across was the statistics estimation for varchar columns. In sybase 9.0.2 the first 254 chars have been taken into account, in Sybase 11.0.1 (probably already in 10.x) only the first 32 chars are used, this is bad, if your varchar data is only differering in the chars after position 32. This can lead to totally different query behavior when migrating to 11.
answered 21 Jan '10, 15:17