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From Harsh J <ha...@cloudera.com>
Subject Re: What happened in hlog if data are deleted cuased by ttl?
Date Tue, 14 Aug 2012 13:24:00 GMT
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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