[Solr Wiki] Update of "HowToReindex" by ShawnHeisey

[Apache Wiki <wi...@apache.org>]

Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Solr Wiki" for change notification.

The "HowToReindex" page has been changed by ShawnHeisey:
https://wiki.apache.org/solr/HowToReindex?action=diff&rev1=4&rev2=5

Comment:
Added intermediate Solr alternative.

  
  There is at least one large-scale Solr user that uses separate Solr instances as intermediate data stores because it's difficult to obtain the data from the original source for a reindex.  When they index new content, it goes into a copy of Solr configured for storage only, not in-depth searching.  Their main Solr instance uses SolrEntityProcessor to import from the intermediate Solr servers, so they can always reindex.
  
+ == Alternatives when a traditional reindex isn't possible ==
+ 
+ Sometimes the option of "do your indexing again" is difficult.  Perhaps the original data is very slow to access, or it may be difficult to get in the first place.  One way to deal with this is to set up an additional Solr instance or additional Solr core whose only job is to store the data in a non-distributed index, then use the SolrEntityProcessor in the DataImportHandler to index from that instance to your real Solr install.  If you need to reindex, just run the import again on your real installation.  Your schema for the intermediate Solr install would have stored="true" and indexed="false" for all fields, and would only use basic types like int, tint, and string.  It would not have any copyFields.
+ 
+ This is the approach used by the Smithsonian for their Solr installation, because getting access to the source databases for the individual entities within the organization is very difficult.  This way they can reindex the online Solr at any time without having to get special permission from all those entities.
+