The timestamp is the time the record was inserted into the Cassandra node. It's used for conflict resolution, so if two clients insert different data into the same row/column, Cassandra can pick the "winner" (most recent timestamp).
You can set it manually on insert, otherwise the node will pick the current time for you (this is a major reason why you want all your Cassandra nodes clocks synchronized via NTP by the way). It's also available to be read, but I don't recall any API available (Hector or otherwise) which allows you to search based on the timestamp value. On Tue, Jan 15, 2013 at 11:51 AM, Renato Marroquín Mogrovejo <renatoj.marroq...@gmail.com> wrote: > Hi Aaron, > > Thanks for answering! Yeah that is what I did but then when looking > into the actual column family created I saw this timestamp column > which Cassandra had created. Are we allowed to use this? What is this > specifically for? > Thanks again for the help! > > > Renato M. > > 2013/1/15 Aaron Turner <synfina...@gmail.com>: >> I don't think so. Usually you'd use either a Time-UUID or something >> like epoch time as the column name to get a range of columns by time >> range. >> >> On Tue, Jan 15, 2013 at 10:46 AM, Renato Marroquín Mogrovejo >> <renatoj.marroq...@gmail.com> wrote: >>> Hi all, >>> >>> I am having some problems while retrieving some events from a column >>> family I have created. >>> My column family has been created as follows: >>> >>> create column family click_event >>> WITH comparator = UTF8Type and >>> column_metadata = [ {column_name: event, validation_class: UTF8Type} ]; >>> >>> My table is populated as follows: >>> >>> list click_events; >>> ------------------- >>> => (column=start:2013-01-13 18:14:59.244, value=, >>> timestamp=1358118943979000) >>> => (column=stop:2013-01-13 18:15:56.793, >>> value=323031332d30312d31332031383a31353a35382e333437, >>> timestamp=1358118960946000) >>> >>> I have two questions here: >>> 1) What is the timestamp column used for? >>> 2) How can I retrieve this timestamp column using Hector client? >>> >>> Thanks in advance! >>> >>> >>> Renato M. >> >> >> >> -- >> Aaron Turner >> http://synfin.net/ Twitter: @synfinatic >> http://tcpreplay.synfin.net/ - Pcap editing and replay tools for Unix & >> Windows >> Those who would give up essential Liberty, to purchase a little temporary >> Safety, deserve neither Liberty nor Safety. >> -- Benjamin Franklin >> "carpe diem quam minimum credula postero" -- Aaron Turner http://synfin.net/ Twitter: @synfinatic http://tcpreplay.synfin.net/ - Pcap editing and replay tools for Unix & Windows Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety. -- Benjamin Franklin "carpe diem quam minimum credula postero"