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From Emmanuel Lecharny <elecha...@gmail.com>
Subject Re: Rdn and Ava cleanup
Date Thu, 24 Feb 2011 13:34:40 GMT
On 2/24/11 2:50 AM, Alex Karasulu wrote:
> On Wed, Feb 23, 2011 at 8:51 PM, Stefan Seelmann<seelmann@apache.org>  wrote:
>> It made me think that maybe using a hashed index for Rdn is probably a
>>> better idea, because then we won't need this comparison to be done (the
>>> equals method would be enough) and also because it would be faster (finding
>>> an element in a Hash table is an O(1) operation - at least, theorically -
>>> when looking in a BTree is an O(log2(N)))
>> I think in the current state the RDN index doesn't need to be ordered
>> data structure, a hash table is sufficient.
>>
>> However we still need to cleanup the backends. One idea I had is to
>> get rid of the onlevel and sublevel index and use the RDN index
>> instead. I did that in the HBase prototype where the onelevel and
>> sublevel index are no physical indexes but backed by the RDN index
>> table. But if we do that then I think the RDN index needs to be a
>> ordered data structure to be able to traverse the index using a
>> cursor.
> Yes we need an ordered index and hence we need to be able to compare
> two RDN values to sort.
we can use the Rdn Hashcode to do that, no ?
> I never considered making the onelevel and sublevel indices backed by
> the RDN index. It makes sense to do this and would improve performance
> because there's less house keeping to do and less IO on separate
> indices.
>
> Interesting.
To be investigated, sure.

-- 
Regards,
Cordialement,
Emmanuel L├ęcharny
www.iktek.com


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