[elephant-devel] QDBM Support

[Ian Eslick]

Does QDBM have inverted indices that work against their main BTrees?   
The Odium API looks like me like it is specialized on text data.

You can do range queries over B-trees with several of QDBM's  
interfaces, but it doesn't look like the system links to the value  
indexed by a primary key from one BTree to another...  That would  
require a separate BTree lookup for each secondary index lookup rather  
than a simple pointer chase.

I'm sure this could be done, but I don't know what the end-to-end  
performance implications are, how easy it would be to do, etc.  I  
suspect that the BDB implementation is a good template, so if you  
wanted to take on this problem I'd be happy to help.  Henrik did a  
pretty good job of doing his own data store implementation without  
much input from us, so it is possible!  :)

Ian

On Feb 12, 2008, at 11:58 PM, Rangarajan Krishnamoorthy wrote:

> Hi,
> I recently purchased LispWorks for Windows. Downloaded Elephant and  
> was able to make it work with BDB. Thanks (and congrats!) for such a  
> nice package. I have heard that QDBM is much better than BDB in  
> terms of performance and does not have the same licensing issues  
> (there are royalty payments for embeding BDB in an application). Do  
> you have any idea of supporting QDBM or another similar backend? I  
> saw that you plan to develop a native implementation. That is great  
> news, but when will that happen?
>
> I am unable to use Allegro Common Lisp (and ACache) because of HUGE  
> royalties, so I am looking at Elephant.
>
> Regards,
> Rangarajan
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