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From jmozah <jmo...@gmail.com>
Subject Re: What happened in hlog if data are deleted cuased by ttl?
Date Tue, 21 Aug 2012 15:29:28 GMT
This helped me http://hadoop-hbase.blogspot.in/2011/12/deletion-in-hbase.html

HBase Musings

On 14-Aug-2012, at 6:54 PM, Harsh J <harsh@cloudera.com> wrote:

> Hi Yonghu,
> A timestamp is stored along with each insert. The ttl is maintained at
> the region-store level. Hence, when the log replays, all entries with
> expired TTLs are automatically omitted.
> Also, TTL deletions happen during compactions, and hence do not
> carry/need Delete events. When scanning a store file, TTL-expired
> entries are automatically skipped away.
> On Tue, Aug 14, 2012 at 3:34 PM, yonghu <yongyong313@gmail.com> wrote:
>> My hbase version is 0.92. I tried something as follows:
>> 1.Created a table 'test' with 'course' in which ttl=5.
>> 2. inserted one row into the table. 5 seconds later, the row was deleted.
>> Later when I checked the log infor of 'test' table, I only found the
>> inserted information but not deleted information.
>> Can anyone tell me which information is written into hlog when data is
>> deleted by ttl or in this situation, no information is written into
>> the hlog. If there is no information of deletion in the log, how can
>> we guarantee the data recovered by log are correct?
>> Thanks!
>> Yong
> -- 
> Harsh J

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