blank fields in Oracle

I have a fairly large application we just migrated from Sybase to Oracle. The application is a moderately large, traditional client/server, decision support tool. The GUI interface I wrote was developed in Borland Delphi and uses ADO to connect to the database (Oracle OLEDB Provider for 9i). The end-users also use MS Access to develop and run ad hoc queries via ODBC (Oracle ODBC driver for 9i). Oracle is new here and our database group really isn't experienced in configuring the database for this sort of application (they usually take the system defaults). So far our performance is dramatically worse than when using Sybase. Our database admin folks are trying different configuration settings and have improved things. Query performance now is only 5-10 times worse than Sybase instead of the 20-50 times worse it was originally. However, I'm fairly sure our db support people will get a handle on the worst of our performance problems eventually.

There is one problem that I hope someone here can help with. We load this database with fresh data every night from mainframe (IDMS) extracts. We'd like to trim blanks during the load but we have a number of fields contain blanks as valid values (for example, a blank in the gift-type-code fields of our donations indicates a cash or deposit gift). Don't tell me that blank fields should be null. There is a difference between null and blank and null makes ad hoc queries difficult for end-users. Besides we're dealing with legacy data that cannot be changed in the short-run. What we really need is for Oracle to recognize the zero-length string or to allow us to trim blanks from most fields but specify a default value of 1 space. It appears the default statement only allows zero or null. I need Oracle to not treat single spaces or blank fields as null during loads.

Any help will be greatly appreciated.

--
================================
Ray Porter
Applications Analyst Programmer
Administrative Information Services, UNC-CH
Phone: (919) 966-5878
Fax: (919) 962-5840
Email: ray_porter_at_unc.edu
Web: http://www.unc.edu/~dragon