queryResultCache's size is not increasing

[Lee Chunki]

Hi,

I am running Solr 4.1.0 and trying to use queryResultCache
but “size” value at admin page is extremely smaller than incoming queries.

I want to know why.

settings and status are as fallow :

* setting - solrconfig.xml
    <queryResultCache class="solr.FastLRUCache"
        size="163840"
        initialSize="163840"
        autowarmCount="10240"/>

* status 
- for 13 hours
  - # of requests : 6,711,920
  - # of unique queries : 72,414
  - size value at admin page : 9

* extra informations
- I want to fetch all result set so we set rows as 1,000,000 
    - but most result number is less 1k
- run ‘full-import’ every five minutes
- use  group, facet and sort when querying 

Thanks,
Chunki.