> I am wondering if TTL values also follow gc_grace? They are purged by the first compaction that processes them after TTL has expired. The TTL expiry is used the same way as the expire on a Tombstone.
Thinking out loud, is this possible…. t0 - write col to all 3 replicas. t1 - overwrite col with a ttl, write to 2 out of 3 replicas. t2 - compaction on all nodes, col removed from 2 out of 3 replicas t3 - read at QUORUM, col written in t0 returns. ExpiringColumn sets it localDeletionTime using the ttl, and cfs.removeDeletedStandard() will purge the column. > The mutation against Column Family "CF_B" is placed last. > If: > get CF_B[def] is 55 > Can I then safely assume that > get CF_A[abc] is 10 OR a newer value The order the changes are applied is undefined (they are pulled from the values of a HashMap). So this should not be relied upon. Cheers ----------------- Aaron Morton Freelance Cassandra Developer @aaronmorton http://www.thelastpickle.com On 21/08/2011, at 11:38 PM, Joris van der Wel wrote: > Hello, > > I have a ColumnFamily in which all columns are always set with a TTL, > this would be one of the hottest column families (rows_cached is set > to 1.0). I am wondering if TTL values also follow gc_grace? If they > do, am I correct in thinking it would be best to set gc_grace really > low in this case? (zero?) > > Another question: > For a single key I have data in ColumnFamily "CF_A" and ColumnFamily > "CF_B". I set their data in one thrift "batch_mutate". > If I understood correctly, atomicity is then guaranteed (if one > mutation fails, they all fail). But isolation is not. However if for > example the following Mutation takes place: > > batch_mutate({ > "mykey": { > "CF_A": [ > Mutation { > column_or_supercolumn: ColumnOrSuperColumn { > column: { > name: "abc", > value: 10, > timestamp: 1313918714729 > } > } > } > ], > "CF_B": [ > Mutation { > column_or_supercolumn: ColumnOrSuperColumn { > column: { > name: "def", > value: 55, > timestamp: 1313918714730 > } > } > }, > ] > } > }, QUORUM) > > The mutation against Column Family "CF_B" is placed last. > If: > get CF_B[def] is 55 > Can I then safely assume that > get CF_A[abc] is 10 OR a newer value > > > Thanks, > Gr. Joris
