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From Ted Yu <yuzhih...@gmail.com>
Subject Re: Storing data with long history of versions
Date Mon, 10 Nov 2014 15:33:14 GMT
Half a million timestamps with 20 bytes each cell equate to 10MB.
That should be fine for your client.

Cheers

On Mon, Nov 10, 2014 at 7:23 AM, Bill Q <bill.q.hdp@gmail.com> wrote:

> Hi Ted,
> Thanks a lot for the reply.
>
> For #1, the size for the value only will be around 20 bytes for each cell.
> And there will be hundreds of thousands of time stamp per cell. But not
> millions. Any suggestion?
>
> Many thanks.
>
>
> Cao
>
> On Monday, November 10, 2014, Ted Yu <yuzhihong@gmail.com> wrote:
>
> > For #1, what's the expected size of data you want to store ?
> >
> > For #2, the new data inserted under column:value with a newer timestamp
> > would be stored in a different HFile. Old and new data would be
> > consolidated after major compaction.
> >
> > Cheers
> >
> > On Mon, Nov 10, 2014 at 6:21 AM, Bill Q <bill.q.hdp@gmail.com
> > <javascript:;>> wrote:
> >
> > > Hi,
> > > I am designing a schema to store time series data for each device. And
> I
> > > have a couple of questions that I am not quit sure.
> > >
> > > 1. *Is there any down side for storing the data in the same
> > > columnfamily:column with a long history of customized timestamp? *
> > >
> > > For example, I have historical daily data for a device. I would like to
> > use
> > > only one column qualifier to store them with custom timestamp, which is
> > the
> > > date of the data was collected. So, when I query the data I can easily
> > pull
> > > all the timeseries data against this particular device in one scan.
> > >
> > > 2. *After a storefile is finalized and become immutable, what would
> > happen
> > > when someone updates the row? *
> > >
> > > For example, if I insert a new column:value with a newer timestamp into
> > the
> > > same row:columnfamily. Where is this new key/value part going to sit in
> > the
> > > HDFS? Is it close to the previous K/V pairs in the storefile?
> > >
> > >
> > > Many thanks.
> > >
> > >
> > > Bill
> > >
> >
>
>
> --
> Many thanks.
>
>
> Bill
>

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