Forum OpenACS Q&A: Response to Installation Guide, downloads

Just take care in defining tables and writing SQL queries in your customization work, and moving code shouldn't be difficult.  Moving data might be a pain, though, since the Oracle version using CLOBs for  everything interesting (like forum posts) and we just use lztext (a compressed text type) in Postgres (which doesn't support CLOB).

Read the guide on porting from Oracle to Postgres to get an idea for what you should avoid in terms of language features, i.e. outer joins and some other stuff.