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From PG <pengyunm...@gmail.com>
Subject Re: When does HBase set modification timestamp of a HFile?
Date Sun, 21 Oct 2012 11:03:43 GMT
Hi, for the record, I have tried fs api as well, and they are the same with each other. 
Regards,
Yun

On Oct 21, 2012, at 12:45 AM, lohit <lohit.vijayarenu@gmail.com> wrote:

> Looks like StoreFile.getModificationTime is returning you in seconds
> precision.
> I am not sure what other APIs could be used here, but if you know the
> location of StoreFile try one of the FileSystem APIs
> http://hadoop.apache.org/docs/current/api/org/apache/hadoop/fs/FileStatus.html#getModificationTime()
> 
> 
> 2012/10/20 yun peng <pengyunmomo@gmail.com>
> 
>> Hi lohit and Stack,
>> You are right, it always ends with 000. My setup in the test is hbase
>> 0.94.2 running on local vfs.  Is this tied with current hbase
>> implementation or something to do with my particular setup (so I can
>> re-configure to make it more precise)?
>> Thanks,
>> Yun
>> 
>> On Sat, Oct 20, 2012 at 7:54 PM, lohit <lohit.vijayarenu@gmail.com> wrote:
>>> Last 3 digits of the timestamp you got from fetching
>> getModificationTime()
>>> has all zeros 1350764448000
>>> Do you get all zeros all the time? May be the time precision is not what
>>> you are looking for here?
>>> 
>>> 2012/10/20 yun peng <pengyunmomo@gmail.com>
>>> 
>>>> Hi, All,
>>>> I am trying to understand how and when hbase set the modification
>>>> timestamp for hfiles. My original intention is to get a timestamp when
>>>> a hfile is generated (when last write to a hfile in compaction).
>>>> StoreFile.getModificationTime() looks a good candidate but after
>>>> initial tests, it has some behaviour that confuses.
>>>> 
>>>> My test case is like,
>>>> @hbase shell
>>>> put 'usertable', "key1", 'cf:c1', "v1"
>>>> put 'usertable', "key1", 'cf:c1', "v2"
>>>> get 'usertable', 'key1', {COLUMN => 'cf:c1', VERSIONS => 4}
>>>> flush 'usertable'
>>>> major_compact 'usertable'
>>>> 
>>>> for the get operation, it echoes
>>>> COLUMN             CELL
>>>> cf:c1             timestamp=1350764448150, value=v2
>>>> cf:c1             timestamp=1350764448114, value=v1
>>>> 
>>>> but when I try to get modification timestamp of the hfile generated by
>>>> major_compact, it is 1350764448000, which is smaller/earlier than that
>>>> of the keyvalues (which are actually put first). I have run the same
>>>> test this couple of times, and it is not always: sometime modification
>>>> timestamp is eariler sometimes it's later than keyvalue's.
>>>> 
>>>> Anyone knows how HBase set modification timestamp of hfile and that of
>>>> a keyvalue pair? Or generally, how should I get a timestamp indicating
>>>> when the last write to a hfile occurs?
>>>> 
>>>> regards,
>>>> Yun
>>>> 
>>> 
>>> 
>>> 
>>> --
>>> Have a Nice Day!
>>> Lohit
>> 
> 
> 
> 
> -- 
> Have a Nice Day!
> Lohit

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