"I am slightly confused now. Time to live is used in networking , after n
hops drop this packet. Also used I'm memcache , expire this data n seconds
after insert. I do not know of any specific ttl features in rdbms so I do not 
understand
why someone would expect  ttl to he permanently durable."

Edward, my mistake was originally assuming that the TTL applied only to *old* 
versions of a cell (I.e. not the most recent one). It was a misunderstanding on 
my part, based on the fact that there *are* no TTL features in an RDBMS (you 
only get rid of the current value by issuing an explicit delete).

HBase is light years ahead of an RDBMS in the way it explicitly handles the 
time dimension; I just wasn't expecting this facet of that behavior. It's part 
of the mindset shift you have to go through coming from a database world to a 
NoSQL world; you can treat parts of your store as a transient cache if you want 
to (which is useful in all kinds of situations). Just needed to expand my brain 
to consider that ... :)

Ian


On Aug 14, 2011, at 7:30 AM, "Edward Capriolo" 
<[email protected]<mailto:[email protected]>> wrote:

I am slightly confused now. Time to live is used in networking , after n
hops drop this packet. Also used I'm memcache , expire this data n seconds
after insert.

I do not know of any specific ttl features in rdbms so I do not understand
why someone would expect  ttl to he permanently durable.

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