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From yuzhih...@gmail.com
Subject Re: Disk Seeks and Column families
Date Sat, 21 Jan 2012 15:33:21 GMT
Have you considered using AggregationProtocol to perform aggregation ?

Thanks



On Jan 20, 2012, at 11:08 PM, Praveen Sripati <praveensripati@gmail.com> wrote:

> Hi,
> 
> 1) According to the this url (1), HBase performs well for two or three
> column families. Why is it so?
> 
> 2) Dump of a HFile, looks like below. The contents of a row stay together
> like a regular row-oriented database. If the column family has 100 column
> family qualifiers and is dense then the data for a particular column family
> qualifier is spread wide. If I want to do an aggregation on a particular
> column identifier, the disk seeks doesn't seems to be much better than a
> regular row-oriented database.
> 
> Please correct me if I am wrong.
> 
> K: row-550/colfam1:50/1309813948188/Put/vlen=2 V: 50
> K: row-550/colfam1:50/1309812287166/Put/vlen=2 V: 50
> K: row-551/colfam1:51/1309813948222/Put/vlen=2 V: 51
> K: row-551/colfam1:51/1309812287200/Put/vlen=2 V: 51
> K: row-552/colfam1:52/1309813948256/Put/vlen=2 V: 52
> 
> (1) - http://hbase.apache.org/book/number.of.cfs.html
> 
> Thanks,
> Praveen

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