Whilst parsing text files using Batch Apex, we retrieved an Heap Size error. The Heap Size limit happens before our custom Iterator. Because we parse an attachment, change it into a Blob and then retrieve 1 large String value. This transformation from Blob to String is providing the issue. The Blob itself has a very small Heap size but when we transform it to a String, the heap size easily quadruples. Is there a way to create an Iterator on a Blob object? I'm assuming that this is not possible since we cannot use any 'split' functions on a Blob file.