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From Mike Drob <mad...@cloudera.com>
Subject Re: unique list of columns
Date Sat, 22 Feb 2014 16:47:41 GMT
There's not a single good way that I am aware of, but there are a couple
ways that will get you close.

First, you can use the SortedKeyIterator to truncate values and potentially
save yourself a lot of data transfer.
Second, each RFile header block will track the columns contained, up to
1000 (possibly configurable). Check out PrintInfo[1].

Mike

[1]:
https://github.com/apache/accumulo/blob/master/core/src/main/java/org/apache/accumulo/core/file/rfile/PrintInfo.java


On Sat, Feb 22, 2014 at 11:25 AM, Arshak Navruzyan <arshakn@gmail.com>wrote:

> I don't know the inner workings of the Rfiles enough but I was wondering
> if there is a faster way to get a unique list of columns in Accumulo (short
> of doing a full mapreduce).  Is there some way to skip ahead all the
> volumes and just get to the next column?
>
> Thanks
>

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