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From Takenori Sato <ts...@cloudian.com>
Subject Re: questions related to the SSTable file
Date Wed, 18 Sep 2013 00:46:53 GMT
> So in fact, incremental backup of Cassandra is just hard link all the new
SSTable files being generated during the incremental backup period. It
could contain any data, not just the data being update/insert/delete in
this period, correct?

Correct.

But over time, some old enough SSTable files are usually shared across
multiple snapshots.


On Wed, Sep 18, 2013 at 3:37 AM, java8964 java8964 <java8964@hotmail.com>wrote:

> Another question related to the SSTable files generated in the incremental
> backup is not really ONLY incremental delta, right? It will include more
> than delta in the SSTable files.
>
> I will use the example to show my question:
>
> first, we have this data in the SSTable file 1:
>
> rowkey(1), columns (maker=honda).
>
> later, if we add one column in the same key:
>
> rowkey(1), columns (maker=honda, color=blue)
>
> The data above being flushed to another SSTable file 2. In this case, it
> will be part of the incremental backup at this time. But in fact, it will
> contain both old data (make=honda), plus new changes (color=blue).
>
> So in fact, incremental backup of Cassandra is just hard link all the new
> SSTable files being generated during the incremental backup period. It
> could contain any data, not just the data being update/insert/delete in
> this period, correct?
>
> Thanks
>
> Yong
>
> > From: Dean.Hiller@nrel.gov
> > To: user@cassandra.apache.org
> > Date: Tue, 17 Sep 2013 08:11:36 -0600
>
> > Subject: Re: questions related to the SSTable file
> >
> > Netflix created file streaming in astyanax into cassandra specifically
> because writing too big a column cell is a bad thing. The limit is really
> dependent on use case….do you have servers writing 1000's of 200Meg files
> at the same time….if so, astyanax streaming may be a better way to go there
> where it divides up the file amongst cells and rows.
> >
> > I know the limit of a row size is really your hard disk space and the
> column count if I remember goes into billions though realistically, I think
> beyond 10 million might slow down a bit….all I know is we tested up to 10
> million columns with no issues in our use-case.
> >
> > So you mean at this time, I could get 2 SSTable files, both contain
> column "Blue" for the same row key, right?
> >
> > Yes
> >
> > In this case, I should be fine as value of the "Blue" column contain the
> timestamp to help me to find out which is the last change, right?
> >
> > Yes
> >
> > In MR world, each file COULD be processed by different Mapper, but will
> be sent to the same reducer as both data will be shared same key.
> >
> > If that is the way you are writing it, then yes
> >
> > Dean
> >
> > From: Shahab Yunus <shahab.yunus@gmail.com<mailto:shahab.yunus@gmail.com
> >>
> > Reply-To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>"
> <user@cassandra.apache.org<mailto:user@cassandra.apache.org>>
> > Date: Tuesday, September 17, 2013 7:54 AM
> > To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>" <
> user@cassandra.apache.org<mailto:user@cassandra.apache.org>>
> > Subject: Re: questions related to the SSTable file
> >
> > derstand if following changes apply to the same row key as above
> example, additional SSTable file could be generated. That is
>

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