Hi Carlo, As Jonathan mentions the compareWith on a column family def. is defines the order for the columns *within* a row... In order to control the ordering of rows you'll need to use the OrderPreservingPartitioner (http://www.datastax.com/docs/0.7/operations/clustering#tokens-partitioners-ring).
As for getColumnsFromRows; it should be returning you a map of lists. The map is insertion-order-preserving and populated based on the provided list of row keys (so if you iterate over the entries in the map they should be in the same order as the list of row keys). The list for each row entry are definitely in the order that Cassandra provides them, take a look at org.scale7.cassandra.pelops.Selector#toColumnList if you need more info. Cheers, Dan -- Dan Washusen Sent with Sparrow On Saturday, 19 February 2011 at 8:16 AM, cbert...@libero.it wrote: > Hi all, > I created a CF in which i need to get, sorted by time, the Rows inside. Each > Row represents a comment. > > <ColumnFamily name="Comments" compareWith="TimeUUIDType" / > > > I've created a few rows using as Row Key a generated TimeUUID but when I call > the Pelops method "GetColumnsFromRows" I don't get the data back as I expect: > rows are not sorted by TimeUUID. > I though it was probably cause of the random-part of the TimeUUID so I create > a new CF ... > > <ColumnFamily name="Comments2" compareWith="LongType" / > > > This time I created a few rows using the java System.CurrentTimeMillis() that > retrieve a long. I call again the "GetColumnsFromRows" and again the same > results: data are not sorted! > I've read many times that Rows are sorted as specified in the compareWith but > I can't see it. > To solve this problem for the moment I've used a SuperColumnFamily with an > UNIQUE ROW ... but I think this is just a workaround and not the solution. > > <ColumnFamily name="Comments" type="Super" compareWith="TimeUUIDType" > CompareSubcolumnsWith="BytesType"/ > > > Now when I call the "GetSuperColumnsFromRow" I get all the SuperColumns as I > expected: sorted by TimeUUID. Why it does not happen the same with the Rows? > I'm confused. > > TIA for any help. > > Best Regards > > Carlo >
