for 4.0 FINAL, redundently list the 'Upgrading from' sections from the BETA and ALPHA releases since there is important info there for any users upgrading from the last 'stable' 3.6 release

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1388288 13f79535-47bb-0310-9956-ffa450edef68

solr/CHANGES.txt

@@ -47,6 +47,76 @@ for more details.
 If you are using SolrCloud's distributed update request capabilities and a non
 string type id field, you must re-index.
 
+Upgrading from Solr 4.0.0-ALPHA
+----------------------
+
+Solr is now much more strict about requiring that the uniqueKeyField feature 
+(if used) must refer to a field which is not multiValued.  If you upgrade from 
+an earlier version of Solr and see an error that your uniqueKeyField "can not 
+be configured to be multivalued" please add 'multiValued="false"' to the 
+<field /> declaration for your uniqueKeyField.  See SOLR-3682 for more details.
+
+In addition, please review the notes above about upgrading from 4.0.0-BETA
+
+Upgrading from Solr 3.6
+----------------------
+
+* The Lucene index format has changed and as a result, once you upgrade, 
+  previous versions of Solr will no longer be able to read your indices.
+  In a master/slave configuration, all searchers/slaves should be upgraded
+  before the master.  If the master were to be updated first, the older
+  searchers would not be able to read the new index format.
+
+* Setting abortOnConfigurationError=false is no longer supported
+  (since it has never worked properly).  Solr will now warn you if
+  you attempt to set this configuration option at all. (see SOLR-1846)
+
+* The default logic for the 'mm' param of the 'dismax' QParser has
+  been changed.  If no 'mm' param is specified (either in the query,
+  or as a default in solrconfig.xml) then the effective value of the
+  'q.op' param (either in the query or as a default in solrconfig.xml
+  or from the 'defaultOperator' option in schema.xml) is used to
+  influence the behavior.  If q.op is effectively "AND" then mm=100%.
+  If q.op is effectively "OR" then mm=0%.  Users who wish to force the
+  legacy behavior should set a default value for the 'mm' param in
+  their solrconfig.xml file.
+  
+* The VelocityResponseWriter is no longer built into the core.  Its JAR and
+  dependencies now need to be added (via <lib> or solr/home lib inclusion),
+  and it needs to be registered in solrconfig.xml like this:
+    <queryResponseWriter name="velocity" class="solr.VelocityResponseWriter"/>
+
+* The update request parameter to choose Update Request Processor Chain is 
+  renamed from "update.processor" to "update.chain". The old parameter was
+  deprecated but still working since Solr3.2, but is now removed
+  entirely.
+
+* The <indexDefaults> and <mainIndex> sections of solrconfig.xml are discontinued
+  and replaced with the <indexConfig> section. There are also better defaults.
+  When migrating, if you don't know what your old settings mean, simply delete
+  both <indexDefaults> and <mainIndex> sections. If you have customizations,
+  put them in <indexConfig> section - with same syntax as before.
+
+* Two of the SolrServer subclasses in SolrJ were renamed/replaced.
+  CommonsHttpSolrServer is now HttpSolrServer, and 
+  StreamingUpdateSolrServer is now ConcurrentUpdateSolrServer.
+
+* The PingRequestHandler no longer looks for a <healthcheck/> option in the 
+  (legacy) <admin> section of solrconfig.xml.  Users who wish to take 
+  advantage of this feature should configure a "healthcheckFile" init param 
+  directly on the  PingRequestHandler.  As part of this change, relative file 
+  paths have been fixed to be resolved against the data dir.  See the example 
+  solrconfig.xml and SOLR-1258 for more details.
+
+* Due to low level changes to support SolrCloud, the uniqueKey field can no 
+  longer be populated via <copyField/> or <field default=...> in the 
+  schema.xml.  Users wishing to have Solr automatically generate a uniqueKey 
+  value when adding documents should instead use an instance of
+  solr.UUIDUpdateProcessorFactory in their update processor chain.  See 
+  SOLR-2796 for more details.
+
+In addition, please review the notes above about upgrading from 4.0.0-BETA, and 4.0.0-ALPHA
+
 Detailed Change List
 ----------------------