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From Dylan Hutchison <dhutc...@uw.edu>
Subject Re: how to maintain versioning in D4M schema?
Date Fri, 27 Nov 2015 07:15:44 GMT
In order to store five versions of a key but return only one of them during
a scan, set the minc and majc VersioningIterator to 5 and set the scan
VersioningIterator to 1.  You can set scanning iterators on a per-scan
basis if this helps.

It is not necessary to put the timestamp in the column family if you are
going with the VersioningIterator approach.

There are many ways to achieve versioning in Accumulo.  As the
designer/programmer, you must choose one that fits your application, of
which we do not know the full details.  It sounds like you have narrowed
your choice to (1) putting the timestamp in the column family, or (2) not
putting the timestamp anywhere else but instead changing the
VersioningIterator such that Accumulo stores more versions than the latest
version of a (row,colfam,colqual,colvis) key.



On Thu, Nov 26, 2015 at 8:45 PM, mohit.kaushik <mohit.kaushik@orkash.com>
wrote:

> David,
>
> But this is the case when we store versions based on timestamp field. The
> point is, in D4M schema we can not achieve it by doing this. In this case
> we are considering CF to store timestamp in reverse order as described by
> Dylan. Then how can we configure Accumulo to return only latest version and
> store only 5 versions?
>
> Thanks
> Mohit Kaushik
>
> On 11/27/2015 09:54 AM, David Medinets wrote:
>
> From the user manual:
>
> user@myinstance mytable> config -t mytable -s table.iterator.scan.vers.opt.maxVersions=5user@myinstance
mytable> config -t mytable -s table.iterator.minc.vers.opt.maxVersions=5user@myinstance
mytable> config -t mytable -s table.iterator.majc.vers.opt.maxVersions=5
>
>
> On Thu, Nov 26, 2015 at 11:10 PM, shweta.agrawal <
> shweta.agrawal@orkash.com> wrote:
>
>> I want to maintain 5 versions only and user can enter any number of
>> versions but I want to keep only 5 latest version.
>>
>>
>> On Friday 27 November 2015 09:38 AM, David Medinets wrote:
>>
>> Do you want five versions of every entry or will the number of versions
>> vary?
>>
>> On Thu, Nov 26, 2015 at 10:53 PM, shweta.agrawal <
>> shweta.agrawal@orkash.com> wrote:
>>
>>> Thanks Dylan and David.
>>> I can store version information in column family. But my problem is when
>>> I have many versions of the same key how will I manage that. In Accumulo
>>> versioning I can specify that how many versions I want to manage.
>>>
>>> Suppose I have 10 versions and I only want 5 versions to store, how to
>>> manage this in a big table?
>>>
>>> Thanks
>>> Shweta
>>>
>>> On Thursday 26 November 2015 10:22 PM, David Medinets wrote:
>>>
>>> What are the query patterns? If you are versioning for auditing then
>>> changing the VersioningIterator seems the easiest approach. You could also
>>> store application-specific version information in the column family. One of
>>> the reasons that D4M does not use it is to allow application-specific uses.
>>> Using the CF means that any applications that understand D4M would not need
>>> to change their queries to adjust for the version information.
>>>
>>> On Thu, Nov 26, 2015 at 4:26 AM, shweta.agrawal <
>>> shweta.agrawal@orkash.com> wrote:
>>>
>>>> Hi,
>>>>
>>>> I have my data stored in D4M style. I also want to maintain versions of
>>>> different value on the basis of time.  As in D4M style  data is only in
>>>> rowid and colQualifier only.
>>>>
>>>> Is there any way to achieve versioning in D4M schema?
>>>>
>>>> Thanks
>>>> Shweta
>>>>
>>>>
>>>
>>>
>>
>>
>
>
> --
>
> * Mohit Kaushik*
> Software Engineer
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