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Date: Mon, 28 Apr 2008 14:35:58 -0700 (PDT)
From: "Bryan Duxbury (JIRA)" <jira@apache.org>
To: hbase-dev@hadoop.apache.org
Subject: [jira] Commented: (HBASE-47) option to set TTL for columns in hbase
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    [ https://issues.apache.org/jira/browse/HBASE-47?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12592903#action_12592903 ] 

Bryan Duxbury commented on HBASE-47:
------------------------------------

For starters let me note that it appears this patch was cut against 0.2, not 0.1. Patch should be relabeled appropriately.

HColumnDescriptor
 * Let's add a constant to HConstants called "FOREVER" and use that in the code wherever the TTL should be unlimited. Also, can we make it's value -1 instead of 0? 

Memcache
 * Why the use of Date class instead of System.currentTimeMillis()? Is there something I'm missing?
 
HStore
 * In getFull, you do the filtering for expired cells at the store level instead of when you're actually iterating. Why not just not add the cells to the results array at all? You'll use less memory.
 * Same as above in get.
 

> option to set TTL for columns in hbase
> --------------------------------------
>
>                 Key: HBASE-47
>                 URL: https://issues.apache.org/jira/browse/HBASE-47
>             Project: Hadoop HBase
>          Issue Type: New Feature
>          Components: hql, regionserver
>            Reporter: Billy Pearson
>            Priority: Minor
>         Attachments: hbase-ttl-0.1.patch
>
>
> I would like to see the option to have a TTL on the columns in hbase this feature could be helpfully in removing stale data from large datasets with out havening to do a full scan of the dataset and then issuing deletes.
> Example 
> Say I am crawling pages and only refreshing pages based on a set score and some pages doe not get updated over X days the old version of the page gets removed from the data set. 
> Say I am striping out links form html and storing them say a link is removed from a page then I would need to issue a delete statement to remove that links form the data set with a ttl the link data would remove its self if not updated in x secs. These are just examples based on crawling like nutch but I can foresee many apps using this option. 
> This is a feature in bigtables thats is handled when bigtable does garbage-collection.

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