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From "Cornish, Duane C." <Duane.Corn...@jhuapl.edu>
Subject RE: Accumulo lexicographical order
Date Wed, 08 Jan 2014 17:38:57 GMT
Great!  Thanks for all the help!

From: Keith Turner [mailto:keith@deenlo.com]
Sent: Wednesday, January 08, 2014 12:04 PM
To: user@accumulo.apache.org
Subject: Re: Accumulo lexicographical order



On Wed, Jan 8, 2014 at 11:50 AM, Mike Drob <mdrob@mdrob.com<mailto:mdrob@mdrob.com>>
wrote:

Duane,

Most API methods for inserting values take byte arrays or byte sequences directly. The lexographic
order is based on the natural ordering of the bytes, i.e. \x00 sorts before \x01. The methods
that take strings will assume UTF-8 encoding and convert for you. If you find a situation
where this is not the case, please let us know!

The one exception to all of this is the timestamp part of the key, which is stored in numeric
order. I want to say that they are kept in reverse order, but don't remember the exact details
off hand.
Thats correct.  The most recent timestamps are sorted first.  Sorted as signed long.



I'm on my phone, so finding the exact place where this is documented will be a challenge,
but I would expect it to be part of our user manual on accumulo.apache.org<http://accumulo.apache.org>

Mike
On Jan 8, 2014 8:26 AM, "Cornish, Duane C." <Duane.Cornish@jhuapl.edu<mailto:Duane.Cornish@jhuapl.edu>>
wrote:
Accumulo Users,

I know Accumulo keys are sorted in lexicographical order in the tables.  Where can I find
the specification defining that order?  For example, what lexicographical order are symbols
in?  Is the order the same as the numerical order of UTF-8 encoding, ASCII encoding, or some
other encoding scheme?

Thanks in advance,
Duane Cornish


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