If the data is important enough to redact, it is probably important enough to verify that the data is actual gone. Of course, this is a problem for more than just PDF documents. An amusing HR trick is to take a look at Microsoft Word resumes, particular the "Track Changes" history.
The example used here populates the repository with Microsoft Word resumes, indexes it using Oracle Text (interMedia Text), and reads the repository using Java streams from a servlet.
275 Free Microsoft Word Resume Templates | The Muse
Oracle8i and Oracle9i support several types of LOB columns. One type, BLOBs, can house binary information such as audio, video, images, and comments internally in the database. Each row can store up to 4 gigabytes of data. The application described here uses a BLOB data type to store Microsoft Word resumes.