RAMDirectory and inner Structure

[Clarissa Meyer <cm...@googlemail.com>]

Hi,

currently I'm working on a students project including a lucene index. It's a


kind of search engine working on extracted data from the web.
It's working pretty good, but now I'm curious about two things:
- when is it usefull to use a RAMDirectory? Is there a number of documents
in an index that will make it too slow when not using a RAMDirectory or is
there any other hint?
- how are lucene indexes build behind the curtain? How is one organized
inside? I could not find anything about its inner structure.

Thanks for any answers
Clarissa

Re: RAMDirectory and inner Structure

[Ian Lea <ia...@gmail.com>]

Hi

> currently I'm working on a students project including a lucene index. It's a
> kind of search engine working on extracted data from the web.
> It's working pretty good, but now I'm curious about two things:
> - when is it usefull to use a RAMDirectory? Is there a number of documents
> in an index that will make it too slow when not using a RAMDirectory or is
> there any other hint?

Lucene is rarely too slow!  Basically you can use RAMDirectory for
transient indexes that fit in RAM.
Anything else and you'll need to look elsewhere, presumably to
FSDirectory or maybe MMapDirectory

> - how are lucene indexes build behind the curtain? How is one organized
> inside? I could not find anything about its inner structure.

See http://lucene.apache.org/java/3_0_0/fileformats.html


--
Ian.

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