Saving a serialized object into a derby database

Hello,

I'm trying to save some objects into a derby database. The table is
defined with

            sql = "CREATE TABLE simpleMarketPrices(" +
                    "marketId INT NOT NULL PRIMARY KEY, " +
                    "content BLOB , " +
                    "cachedate TIMESTAMP)";

My save function is

    public synchronized void saveObject(String sql,Object obj){

        byte[] b;
        try{
            PreparedStatement ps = conn.prepareStatement(sql);

            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            ObjectOutputStream oout = new ObjectOutputStream(baos);
            oout.writeObject(obj);
            oout.close();

            b = baos.toByteArray();

            ps.setBytes(1, b);
            ps.execute();
            //ps.setInt(2, ++count);

            System.out.println("Data Saved");
        }catch(Exception e){
         System.err.println("Caught an error while trying to save
object, sql is " + sql);
         System.err.println("Error: " + e.getLocalizedMessage());;
         System.exit(0);
        }
    }

I am calling the above function with:

sql = "INSERT INTO simpleMarketPrices(marketId,content,cachedate)
VALUES(" + marketId + ",?,'" + now + "')";

saveObject(sql,this);

where this is an object that I've created.

However, I keep on getting the following error:

Caught an error while trying to save object, sql is INSERT INTO
simpleMarketPrices(marketId,content,cachedate)
VALUES(20643274,?,'2007-10-18 15:59:26.006')
Error: Page Page(2,Container(0, 896)) could not be written to disk,
please check if disk is full.

My disk is not full, so that isn't the problem. And I'm using the SUN
JRE, so it isn't the IBM JRE that's causing this.

Does anyone know how I can resolve this?