Formula for open file descriptors

[Lance Norskog <go...@gmail.com>]

Hi-
 
In early June Mike Klass posted a formula for the number of file descriptors
needed by Solr:
 
	For each segment, 7 + num indexed fields per segment.  
	There should be log_{base mergefactor}(numDocs) * mergeFactor
segments, approximately. 

Is this still true?

Thanks,

Lance Norskog

Re: Formula for open file descriptors

[Mike Klaas <mi...@gmail.com>]

On 18-Sep-07, at 5:39 PM, Lance Norskog wrote:

> Hi-
>
> In early June Mike Klass posted a formula for the number of file  
> descriptors
> needed by Solr:
>
> 	For each segment, 7 + num indexed fields per segment.
> 	There should be log_{base mergefactor}(numDocs) * mergeFactor
> segments, approximately.
>
> Is this still true?

No, it is a constant ~10 files per segment now (no per-field file  
descriptor count).

Unfortunately, I forgot that a set of file descriptors is needed for  
each Reader -- so multiply the total by 2 at least.

The formula's seeming mathematical nature shouldn't be confused for  
precision: I wouldn't use it for anything other than an order-mag  
level estimation of the number of fds needed.

-Mike