I think this is some confusion about the two different usages of timestamp.
The timestamp stored with the column value (not a column of timestamp type) is stored using microsecond scale, it's just a 64 bit int we do not use it as a time value. Each mutation in a single request will have a different timestamp as per https://github.com/apache/cassandra/blob/cassandra-1.2/src/java/org/apache/cassandra/service/QueryState.java#L48 A column of type timestamp is internally stored as a DateTime type which is milliseconds past the epoch https://github.com/apache/cassandra/blob/cassandra-1.2/src/java/org/apache/cassandra/db/marshal/DateType.java Does that help ? ----------------- Aaron Morton Freelance Cassandra Consultant New Zealand @aaronmorton http://www.thelastpickle.com On 29/04/2013, at 3:42 AM, Michael Theroux <mthero...@yahoo.com> wrote: > Hello, > > Just wondering if I can get a quick clarification on some simple CQL. We > utilize Thrift CQL Queries to access our cassandra setup. As clarified in a > previous question I had, when using CQL and Thrift, timestamps on the > cassandra column data is assigned by the server, not the client, unless "AND > TIMESTAMP" is utilized in the query, for example: > > http://www.datastax.com/docs/1.0/references/cql/UPDATE > > According to the Datastax documentation, this timestamp should be: > > "Values serialized with the timestamp type are encoded as 64-bit signed > integers representing a number of milliseconds since the standard base time > known as the epoch: January 1 1970 at 00:00:00 GMT." > > However, my testing showed that updates didn't work when I used a timestamp > of this format. Looking at the Cassandra code, it appears that cassandra > will assign a timestamp of System.currentTimeMillis() * 1000 when a timestamp > is not specified, which would be the number of nanoseconds since the stand > base time. In my test environment, setting the timestamp to be the current > time * 1000 seems to work. It seems that if you have an older installation > without TIMESTAMP being specified in the CQL, or a mixed environment, the > timestamp should be * 1000. > > Just making sure I'm reading everything properly... improperly setting the > timestamp could cause us some serious damage. > > Thanks, > -Mike > >
