Index: conf/nutch-default.xml
===================================================================
--- conf/nutch-default.xml	(revision 1352784)
+++ conf/nutch-default.xml	(working copy)
@@ -469,6 +469,14 @@
 </property>
 
 <property>
+  <name>db.injector.overwrite</name>
+  <value>false</value>
+  <description>Whether existing records in the CrawlDB will be overwritten
+  by injected records.
+  </description>
+</property>
+
+<property>
   <name>db.score.injected</name>
   <value>1.0</value>
   <description>The score of new pages added by the injector.
@@ -900,6 +908,12 @@
 </property>
 
 <property>
+  <name>indexer.add.domain</name>
+  <value>false</value>
+  <description>Whether to add the domain field to a NutchDocument.</description>
+</property>
+
+<property>
   <name>indexer.skip.notmodified</name>
   <value>false</value>
   <description>Whether the indexer will skip records with a db_notmodified status.
Index: src/java/org/apache/nutch/crawl/Injector.java
===================================================================
--- src/java/org/apache/nutch/crawl/Injector.java	(revision 1352784)
+++ src/java/org/apache/nutch/crawl/Injector.java	(working copy)
@@ -152,7 +152,11 @@
 
   /** Combine multiple new entries for a url. */
   public static class InjectReducer implements Reducer<Text, CrawlDatum, Text, CrawlDatum> {
-    public void configure(JobConf job) {}    
+    private boolean overwrite = false;
+    public void configure(JobConf job) {
+      overwrite = job.getBoolean("db.injector.overwrite", false);
+    }
+    
     public void close() {}
 
     private CrawlDatum old = new CrawlDatum();
@@ -162,19 +166,25 @@
                        OutputCollector<Text, CrawlDatum> output, Reporter reporter)
       throws IOException {
       boolean oldSet = false;
+      boolean injectedSet = false;
       while (values.hasNext()) {
         CrawlDatum val = values.next();
         if (val.getStatus() == CrawlDatum.STATUS_INJECTED) {
           injected.set(val);
           injected.setStatus(CrawlDatum.STATUS_DB_UNFETCHED);
+          injectedSet = true;
         } else {
           old.set(val);
           oldSet = true;
         }
       }
       CrawlDatum res = null;
-      if (oldSet) res = old; // don't overwrite existing value
-      else res = injected;
+      
+      if ((injectedSet && overwrite) || (injectedSet && !oldSet)) {
+        res = injected;
+      } else {
+        res = old;
+      }
 
       output.collect(key, res);
     }