You could use my ZLIB implementation which can be used to create and extract .zip files and compress/uncompress blobs for storage in the database. For the database, you'll need to store the original size in a number column because it is an input to the uncompress function. I would also add a compressed size column. That way you could easily write a query to tell you the average compression rate.

http://www.topwizprogramming.com/freecode_zlibwapi.html

As I read you, you want to read document files from disk - to then store that file's content to a BLOB field in the database in a compressed format. Also, you want to extract the stored objects and save them to (compressed) files. Correct?

Now, if I'm correct - here is what I would consider:

• Use PowerBuilder's new Compressor object class which supports compression into ZIP, 7ZIP, GZIP, or TAR format.
• Use the variant of its Compress function working on BLOB data to be "stream"-ish.
• You will need to read the contents of the file from disk into a BLOB - before calling Compress.
• When you have a document in compressed format, you can do any of these:
  • Save it to database using UPDATEBLOB.
  • Save it to file using FileOpen; FileWriteEx; FileClose.
    I would use a file extension that matches the compression type, like ZIP or TAR.
• Alternatively you can read the compressed document into memory by any of these:
  • Read from database using SELECTBLOB.
  • Read from file using FileOpen; FileReadEx, FileClose.
• Un-compress  is called Extract in PowerBuilder.
  • Class = ExtractorObject
  • Function = Extract

PowerBuilder can extract a few more formats than it can compress.

HTH /Michael