Output report to csv -- only one page

If I export a report to csv using:

/biprws/raylight/v1/documents/278496/reports/7

Accept: text/csv

I get the expected result.  But if I try to set the delimiter with:

/biprws/raylight/v1/documents/278496/reports/7?columnDelimiter=Tab

Accept: text/csv

then I only get the first 40 or so lines.  Is there another parameter I need to specify in order to get the whole report?

Also, I was surprised to see that the REST API doesn't support plain text output, although that can be done in WebI.  I tried "text/plain" in the hopes that it was undocumented, but that did not work.  Is it possible to export to plain text in REST?