diff --git a/CHANGELOG b/CHANGELOG
index 55ac0dba3..ed19b544b 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -23,8 +23,8 @@
  - new: anonymize: supports many hash mechanisms (murmur3, sha, md5, etc) as
    well as IP address anonymization (#280, #261; patches by Richard Pijnenburg
    and Avishai Ish-Shalom)
- - filter: date: now accepts 'match' as a setting. Use of this is preferable
-   to the old syntax.
+ - feature: date: now accepts 'match' as a setting. Use of this is preferable
+   to the old syntax. (#248, LOGSTASH-734, Patch by Louis Zuckerman)
  - improvement: grok: now accepts (?<foo>...) named captures. This lets you
    compose a pattern in the grok config without needing to define it in a
    patterns file. Example: (?<hostport>%{HOST}:%{POSINT}) to capture 'hostport'
diff --git a/lib/logstash/filters/mutate.rb b/lib/logstash/filters/mutate.rb
index 3c53551a7..fcf4f362c 100644
--- a/lib/logstash/filters/mutate.rb
+++ b/lib/logstash/filters/mutate.rb
@@ -207,12 +207,14 @@ class LogStash::Filters::Mutate < LogStash::Filters::Base
   def replace(event)
     # TODO(sissel): use event.sprintf on the field names?
     @replace.each do |field, newvalue|
+      next unless event.include?(field)
       event[field] = event.sprintf(newvalue)
     end
   end # def replace
 
   def convert(event)
     @convert.each do |field, type|
+      next unless event.include?(field)
       original = event[field]
 
       # calls convert_{string,integer,float} depending on type requested.
diff --git a/lib/logstash/outputs/elasticsearch.rb b/lib/logstash/outputs/elasticsearch.rb
index f4d7deaf3..34ac6945b 100644
--- a/lib/logstash/outputs/elasticsearch.rb
+++ b/lib/logstash/outputs/elasticsearch.rb
@@ -37,8 +37,9 @@ class LogStash::Outputs::ElasticSearch < LogStash::Outputs::Base
   # similar events to the same 'type'. String expansion '%{foo}' works here.
   config :index_type, :validate => :string, :default => "%{@type}"
 
-  # The document ID for the index. Overwrites any existing entry in elasticsearch with the same ID.
-  config :id, :validate => :string, :default => nil
+  # The document ID for the index. Useful for overwriting existing entries in
+  # elasticsearch with the same ID.
+  config :document_id, :validate => :string, :default => nil
 
   # The name of your cluster if you set it on the ElasticSearch side. Useful
   # for discovery.
@@ -163,11 +164,11 @@ class LogStash::Outputs::ElasticSearch < LogStash::Outputs::Base
       end
     end
 
-    if id.nil?
-        req = @client.index(index, type, event.to_hash) 
+    if @document_id.nil?
+      req = @client.index(index, type, event.to_hash) 
     else
-        id = event.sprintf(@id)
-        req = @client.index(index, type, id, event.to_hash)
+      id = event.sprintf(@document_id)
+      req = @client.index(index, type, id, event.to_hash)
     end
 
     increment_inflight_request_count
diff --git a/lib/logstash/outputs/elasticsearch_http.rb b/lib/logstash/outputs/elasticsearch_http.rb
index 8a5e9ce8d..cf493a64c 100644
--- a/lib/logstash/outputs/elasticsearch_http.rb
+++ b/lib/logstash/outputs/elasticsearch_http.rb
@@ -40,6 +40,10 @@ class LogStash::Outputs::ElasticSearchHTTP < LogStash::Outputs::Base
   # be used.
   config :flush_size, :validate => :number, :default => 100
 
+  # The document ID for the index. Useful for overwriting existing entries in
+  # elasticsearch with the same ID.
+  config :document_id, :validate => :string, :default => nil
+
   public
   def register
     require "ftw" # gem ftw
@@ -84,9 +88,12 @@ class LogStash::Outputs::ElasticSearchHTTP < LogStash::Outputs::Base
   end # def receive_single
 
   def receive_bulk(event, index, type)
+    header = { "index" => { "_index" => index, "_type" => type } }
+    if @document_id.nil?
+      header["index"]["_id"] = event.sprintf(@document_id)
+    end
     @queue << [
-      { "index" => { "_index" => index, "_type" => type } }.to_json,
-      event.to_json
+      header.to_json, event.to_json
     ].join("\n")
 
     # Keep trying to flush while the queue is full.
@@ -98,6 +105,10 @@ class LogStash::Outputs::ElasticSearchHTTP < LogStash::Outputs::Base
     puts "Flushing #{@queue.count} events"
     # If we don't tack a trailing newline at the end, elasticsearch
     # doesn't seem to process the last event in this bulk index call.
+    #
+    # as documented here: 
+    # http://www.elasticsearch.org/guide/reference/api/bulk.html
+    #  "NOTE: the final line of data must end with a newline character \n."
     response = @agent.post!("http://#{@host}:#{@port}/_bulk",
                             :body => @queue.join("\n") + "\n")
 
diff --git a/lib/logstash/outputs/elasticsearch_river.rb b/lib/logstash/outputs/elasticsearch_river.rb
index 18075c7f5..e464b0b56 100644
--- a/lib/logstash/outputs/elasticsearch_river.rb
+++ b/lib/logstash/outputs/elasticsearch_river.rb
@@ -80,6 +80,10 @@ class LogStash::Outputs::ElasticSearchRiver < LogStash::Outputs::Base
   # AMQP persistence setting
   config :persistent, :validate => :boolean, :default => true
 
+  # The document ID for the index. Useful for overwriting existing entries in
+  # elasticsearch with the same ID.
+  config :document_id, :validate => :string, :default => nil
+
   public
   def register
 
@@ -199,20 +203,14 @@ class LogStash::Outputs::ElasticSearchRiver < LogStash::Outputs::Base
   public
   def receive(event)
     return unless output?(event)
-
-    # TODO(sissel): Refactor this to not use so much string concatonation.
-
     # River events have a format of
     # "action\ndata\n"
     # where 'action' is index or delete, data is the data to index.
-    index_message = {
-      "index" => { 
-        "_index" => event.sprintf(@index),
-        "_type" => event.sprintf(@index_type)
-      }
-   }.to_json + "\n"
+    header = { "index" => { "_index" => index, "_type" => type } }
+    if @document_id.nil?
+      header["index"]["_id"] = event.sprintf(@document_id)
+    end
 
-    index_message += event.to_json + "\n"
-    @mq.receive_raw(index_message)
+    @mq.receive_raw(header.to_json + "\n" + event.to_json + "\n")
   end # def receive
 end # LogStash::Outputs::ElasticSearchRiver