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https://issues.apache.org/jira/browse/HBASE-47?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12593494#action_12593494
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Bryan Duxbury commented on HBASE-47:
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HColumnDescriptor:
* Update HColumnDescriptor's javadoc to reference HConstants.FOREVER instead
of the actual raw value.
Memcache:
* Instead of having memcache take an HStore, could we just make it take a TTL?
A memcache is only ever for a single column family, and TTL is configured at
the family level. I just don't like the "if (store != null)" stuff that it does
now. The default constructor can just pass a FOREVER TTL to the other
constructor.
* Instead of doing the math to turn TTL seconds into milleseconds during every
call, can we move it into the constructor?
* Line 314: even though it's only a debug message, you should wrap the line
with "if (LOG.isDebugEnabled() {...}". Even though the line won't make it out
to the log, the string will still get evaluated, and we'd like to avoid that
when we're not in debug.
HStore
* Same as above regarding TTL seconds to milleseconds.
Some small items:
* There are tabs in this patch - please replace them with two spaces.
* I like the test, but I'm loath to include another 70 seconds in the test
suite. Can you put the values in the past and see if they are immediately
screened out? That would make it a very fast test.
Overall I really like this patch. This is an impressive feature to take on and
it's been done admirably. Thanks Andrew!
> 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-0.2-r652401.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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