Bigtable Scan.setReversed() not working in version 1.2.1?

Question

I am using JAVA API to scan Bigtable by partial row-key, both backward and forward. This code works well, but ONLY forward:

    Scan s = new Scan();
    s.setReversed(true);    
    s.setStartRow(rowKey);          
    s.setStopRow(rowKeyEnd); 
    ResultScanner scanner = tbl.getScanner(s);
    for (Result row : scanner)
    {   
        String rk = new String(row.getRow());
        System.out.println("Row: " + rk);
    }

It seems like the line .setReversed(true); does not have any impact on its own, regardless of whether I set it before or after setting the start and end row-keys. If I switch start and end row keys in .setStartRow() and .setStopRow(), then I get an Exception in the iteration code (Result row : scanner):
Caused by: com.google.bigtable.repackaged.io.grpc.StatusRuntimeException: INVALID_ARGUMENT: Error in field 'row_ranges' : Error in element #0 : start_key must be less than end_key

As I understand from this discussion when reversing a Scan in HBase, which is the startKey and which is the stopKey?, the Reverse Scan doesn't work in versions below 0.98, but I see my server-side version as 1.2.1 in Google Cloud Console:

hbase(main):023:0> version 1.2.1, r8d8a7107dc4ccbf36a92f64675dc60392f85c015, Wed Mar 30 11:29:35 CDT 2016

Also, my client-side JAR is bigtable-hbase-1.2-0.9.4.jar

My row-keys are formatted in the following fashion, as a test:
John*1*XXX
John*2*XXX
John*3*XXX

Is there a better way to get this done please?

Answer 1

Unfortunately, Bigtable does not support reverse scanning. The HBase API mostly lines up with Cloud Bigtable, but not all. You found one of the missing features in Bigtable.

Answer 2

Reverse scans are now available in Preview.