So, what you're saying is:

http://lmgtfy.com/?q=hbase+ttl+remove+all+versions+except+most+recent

:)

I like the idea of making this pluggable (via the coprocessor framework, or 
otherwise). But I also think this is a fundamental enough policy option that 
making it hard-coded might be a good idea. When I was talking to someone the 
other day about the current TTL policy, he was like, "WTF, who would want that, 
it eats your data?". There's no such thing as a "keep 0 versions" option, and 
thus no way to accidentally lose your most current data using that approach. 
But with the TTL version there is, which is (IMO) counter-intuitive for those 
coming from an RDBMS background.

Commented thusly in the JIRA. :)

Ian

On Aug 13, 2011, at 8:00 PM, lars hofhansl wrote:

Hey Ian, (how are things :)

I just stumbled across https://issues.apache.org/jira/browse/HBASE-4071.

-- Lars


________________________________
From: Ian Varley <[email protected]<mailto:[email protected]>>
To: "[email protected]<mailto:[email protected]>" 
<[email protected]<mailto:[email protected]>>
Sent: Saturday, August 13, 2011 6:51 PM
Subject: TTL for cell values

Hi all,

Quick clarification on TTL for cells. The concept makes sense (instead of "keep 
3 versions" you say "keep versions more recent than time T"). But, if there's 
only 1 value in the cell, and that value is older than the TTL, will it also be 
deleted?

If so, has there ever been discussion of a "TTL except for most recent" option? 
(i.e. you want the current version to be permanently persistent, but also want 
some time-based range of version history, so you can peek back and get 
consistent snapshots within the last hour, 6 hours, 24 hours, etc). TTL seems 
perfect for this, but not if it'll chomp the current version of cells too! :)

Thanks!
Ian

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