[Solr Wiki] Update of "SolrCaching" by StuHood

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The following page has been changed by StuHood:
http://wiki.apache.org/solr/SolrCaching

The comment on the change is:
Adds some hints that Mike Klaas bestowed upon solr-user

------------------------------------------------------------------------------
  
  == filterCache ==
  
- This cache stores '''unordered''' sets of document IDs. 
+ This cache stores '''unordered''' sets of document IDs.
+ 
+ If you use faceting with the fieldCache method (see SolrFacetingOverview), it is recommended that you set the filterCache size to be greater than the number of unique values in all of your faceted fields.
  {{{
      <!-- Internal cache used by SolrIndexSearcher for filters (DocSets),
           unordered sets of *all* documents that match a query.
@@ -57, +59 @@

  
  == queryResultCache ==
  
- This cache stores ''''ordered'''' sets of document IDs &#151; results of a query ordered by some cirteria.  
+ This cache stores '''ordered''' sets of document IDs &#151; results of a query ordered by some criteria.
+ 
+ The memory usage for the queryResultCache is significantly less than that of the filterCache because it only stores document IDs that were returned to the user by the query.
  {{{
      <!-- queryResultCache caches results of searches - ordered lists of
           document ids (DocList) based on a query, a sort, and the range
@@ -72, +76 @@

  
  == documentCache ==
  
+ The documentCache stores Lucene Document objects that have been fetched from disk.
+ 
+ The size for the documentCache should always be greater than <max_results> * <max_concurrent_queries>, to ensure that Solr does not need to refetch a document during a request. The more fields you store in your documents, the higher the memory usage of this cache will be.
+ 
- This cache cannot be used as a source for autowarming because document IDs will change when anything in the index changes so they can't be used by a new searcher.
+ ''(Note: This cache cannot be used as a source for autowarming because document IDs will change when anything in the index changes so they can't be used by a new searcher.)''
  {{{
      <!-- documentCache caches Lucene Document objects (the stored fields for each document).
        -->
@@ -111, +119 @@

  
  == useFilterForSortedQuery ==
  
- If the Filter cache is not enabled, this setting is ignored, but performance ''may'' be impacted if true or false. You may want to try both settings.
+ If the filterCache is not enabled, this setting is ignored, but performance ''may'' be impacted if true or false. You may want to try both settings.
  {{{
      <!-- An optimization that attempts to use a filter to satisfy a search.
           If the requested sort does not include score, then the filterCache
@@ -155, +163 @@

  
  = Tradeoffs =
  
- There will be additional latency due to auto-warming from the time that you request a new searcher to be opened until the time that it becomes "registered".
+ Increasing autoWarming values will cause additional latency due to auto-warming from the time that you request a new searcher to be opened until the time that it becomes "registered".
  
  = Caching and Distribution/Replication =