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From Ian Varley <ivar...@salesforce.com>
Subject Re: TTL for cell values
Date Sun, 14 Aug 2011 15:36:13 GMT
"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" <edlinuxguru@gmail.com<mailto:edlinuxguru@gmail.com>>
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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