diff --git a/scripts/base/frameworks/sumstats/plugins/__load__.bro b/scripts/base/frameworks/sumstats/plugins/__load__.bro
index 3b2bb553e6..c0ee3a6767 100644
--- a/scripts/base/frameworks/sumstats/plugins/__load__.bro
+++ b/scripts/base/frameworks/sumstats/plugins/__load__.bro
@@ -1,4 +1,5 @@
 @load ./average
+@load ./last
 @load ./max
 @load ./min
 @load ./sample
diff --git a/scripts/base/frameworks/sumstats/plugins/last.bro b/scripts/base/frameworks/sumstats/plugins/last.bro
new file mode 100644
index 0000000000..d0587bde08
--- /dev/null
+++ b/scripts/base/frameworks/sumstats/plugins/last.bro
@@ -0,0 +1,49 @@
+@load base/frameworks/sumstats
+@load base/utils/queue
+
+module SumStats;
+
+export {
+	redef record Reducer += {
+		## A number of sample Observations to collect.
+		samples: count &default=0;
+	};
+
+	redef record ResultVal += {
+		## This is the queue where samples are maintained.  Use the
+		## :bro:see:`SumStats::get_samples` function to get a vector of the samples.
+		samples: Queue::Queue &optional;
+	};
+
+	## Get a vector of sample Observation values from a ResultVal.
+	global get_samples: function(rv: ResultVal): vector of Observation;
+}
+
+function get_samples(rv: ResultVal): vector of Observation
+	{
+	local s: vector of Observation = vector();
+	if ( rv?$samples )
+		Queue::get_vector(rv$samples, s);
+	return s;
+	}
+
+hook observe_hook(r: Reducer, val: double, obs: Observation, rv: ResultVal)
+	{
+	if ( r$samples > 0 )
+		{
+		if ( ! rv?$samples )
+			rv$samples = Queue::init([$max_len=r$samples]);
+		Queue::put(rv$samples, obs);
+		}
+	}
+
+hook compose_resultvals_hook(result: ResultVal, rv1: ResultVal, rv2: ResultVal)
+	{
+	# Merge $samples
+	if ( rv1?$samples && rv2?$samples )
+		result$samples = Queue::merge(rv1$samples, rv2$samples);
+	else if ( rv1?$samples )
+		result$samples = rv1$samples;
+	else if ( rv2?$samples )
+		result$samples = rv2$samples;
+	}
diff --git a/scripts/base/frameworks/sumstats/plugins/sample.bro b/scripts/base/frameworks/sumstats/plugins/sample.bro
index dc2f438c79..b04d2cf57c 100644
--- a/scripts/base/frameworks/sumstats/plugins/sample.bro
+++ b/scripts/base/frameworks/sumstats/plugins/sample.bro
@@ -1,49 +1,117 @@
 @load base/frameworks/sumstats/main
-@load base/utils/queue
 
 module SumStats;
 
 export {
+	redef enum Calculation += {
+		## Get uniquely distributed random samples from the observation stream
+		SAMPLE
+	};
+
 	redef record Reducer += {
 		## A number of sample Observations to collect.
-		samples: count &default=0;
+		num_samples: count &default=0;
 	};
 
 	redef record ResultVal += {
-		## This is the queue where samples are maintained.  Use the
-		## :bro:see:`SumStats::get_samples` function to get a vector of the samples.
-		samples: Queue::Queue &optional;
-	};
+		## This is the vector in which the samples are maintained.
+		sample_vector: vector of Observation &default=vector();
 
-	## Get a vector of sample Observation values from a ResultVal.
-	global get_samples: function(rv: ResultVal): vector of Observation;
+		## Number of total observed elements.
+		sample_elements: count &default=0;
+	};
 }
 
-function get_samples(rv: ResultVal): vector of Observation
+redef record ResultVal += {
+	# Internal use only.  This is not meant to be publically available
+	# and just a copy of num_samples from the Reducer. Needed for availability
+	# in the compose hook.
+	num_samples: count &default=0;
+};
+
+hook init_resultval_hook(r: Reducer, rv: ResultVal)
 	{
-	local s: vector of Observation = vector();
-	if ( rv?$samples )
-		Queue::get_vector(rv$samples, s);
-	return s;
+	if ( SAMPLE in r$apply )
+		rv$num_samples = r$num_samples;
 	}
 
+function sample_add_sample(obs:Observation, rv: ResultVal)
+	{
+	++rv$sample_elements;
+
+	if ( |rv$sample_vector| < rv$num_samples )
+		rv$sample_vector[|rv$sample_vector|] = obs;
+	else
+		{
+		local ra = rand(rv$sample_elements);
+		if ( ra < rv$num_samples )
+			rv$sample_vector[ra] = obs;
+		} 
+		
+	}	
+
 hook observe_hook(r: Reducer, val: double, obs: Observation, rv: ResultVal)
 	{
-	if ( r$samples > 0 )
+	if ( SAMPLE in r$apply )
 		{
-		if ( ! rv?$samples )
-			rv$samples = Queue::init([$max_len=r$samples]);
-		Queue::put(rv$samples, obs);
+		sample_add_sample(obs, rv);
 		}
 	}
 
 hook compose_resultvals_hook(result: ResultVal, rv1: ResultVal, rv2: ResultVal)
 	{
-	# Merge $samples
-	if ( rv1?$samples && rv2?$samples )
-		result$samples = Queue::merge(rv1$samples, rv2$samples);
-	else if ( rv1?$samples )
-		result$samples = rv1$samples;
-	else if ( rv2?$samples )
-		result$samples = rv2$samples;
+	if ( rv1$num_samples != rv2$num_samples ) 
+		{
+		Reporter::error("Merging sample sets with differing sizes is not supported");
+		return;
+		}
+	
+	local num_samples = rv1$num_samples;
+
+	if ( |rv1$sample_vector| > num_samples || |rv2$sample_vector| > num_samples )
+		{
+		Reporter::error("Sample vector with too many elements. Aborting.");
+		return;
+		}
+
+
+	if ( |rv1$sample_vector| != num_samples && |rv2$sample_vector| < num_samples )
+		{
+		if ( |rv1$sample_vector| != rv1$sample_elements || |rv2$sample_vector| < rv2$sample_elements )
+			{
+			Reporter::error("Mismatch in sample element size and tracking. Aborting merge");
+			return;
+			}
+
+		for ( i in rv1$sample_vector )
+			sample_add_sample(rv1$sample_vector[i], result);
+
+		for ( i in rv2$sample_vector)
+			sample_add_sample(rv2$sample_vector[i], result);
+		}
+	else 
+		{
+		local other_vector: vector of Observation;
+		local othercount: count;
+		if ( rv1$sample_elements > rv2$sample_elements )
+			{
+			result$sample_vector = copy(rv1$sample_vector);
+			other_vector = rv2$sample_vector;
+			othercount = rv2$sample_elements;
+			}
+		else
+			{
+			result$sample_vector = copy(rv2$sample_vector);
+			other_vector = rv1$sample_vector;
+			othercount = rv1$sample_elements;
+			}
+
+		local totalcount = rv1$sample_elements + rv2$sample_elements;
+
+		for ( i in other_vector ) 
+			{
+			if ( rand(totalcount) <= othercount )
+				result$sample_vector[i] = other_vector[i];
+			}
+		}
 	}
diff --git a/testing/btest/Baseline/scripts.base.frameworks.sumstats.last/.stdout b/testing/btest/Baseline/scripts.base.frameworks.sumstats.last/.stdout
new file mode 100644
index 0000000000..35219765af
--- /dev/null
+++ b/testing/btest/Baseline/scripts.base.frameworks.sumstats.last/.stdout
@@ -0,0 +1,9 @@
+6.5.4.3
+[[num=2, dbl=<uninitialized>, str=<uninitialized>]]
+1
+1.2.3.4
+[[num=5, dbl=<uninitialized>, str=<uninitialized>], [num=51, dbl=<uninitialized>, str=<uninitialized>]]
+20
+7.2.1.5
+[[num=1, dbl=<uninitialized>, str=<uninitialized>]]
+1
diff --git a/testing/btest/scripts/base/frameworks/sumstats/last.bro b/testing/btest/scripts/base/frameworks/sumstats/last.bro
new file mode 100644
index 0000000000..e0cef0ec10
--- /dev/null
+++ b/testing/btest/scripts/base/frameworks/sumstats/last.bro
@@ -0,0 +1,47 @@
+# @TEST-EXEC: bro %INPUT
+# @TEST-EXEC: btest-diff .stdout
+
+event bro_init() &priority=5
+	{
+	local r1: SumStats::Reducer = [$stream="test.metric", 
+	                               $apply=set(SumStats::SAMPLE), $num_samples=2];
+	SumStats::create([$epoch=3secs,
+	                     $reducers=set(r1),
+	                     $epoch_finished(data: SumStats::ResultTable) = 
+	                     	{
+	                     	for ( key in data )
+	                     		{
+					print key$host;
+	                     		local r = data[key]["test.metric"];
+	                     		print r$sample_vector;
+					print r$sample_elements;
+	                     		}
+	                     	}
+		 ]);
+
+	SumStats::observe("test.metric", [$host=1.2.3.4], [$num=5]);
+	SumStats::observe("test.metric", [$host=1.2.3.4], [$num=22]);
+	SumStats::observe("test.metric", [$host=1.2.3.4], [$num=94]);
+	SumStats::observe("test.metric", [$host=1.2.3.4], [$num=50]);
+	# I checked the random numbers. seems legit.
+	SumStats::observe("test.metric", [$host=1.2.3.4], [$num=51]);
+	SumStats::observe("test.metric", [$host=1.2.3.4], [$num=51]);
+	SumStats::observe("test.metric", [$host=1.2.3.4], [$num=51]);
+	SumStats::observe("test.metric", [$host=1.2.3.4], [$num=51]);
+	SumStats::observe("test.metric", [$host=1.2.3.4], [$num=51]);
+	SumStats::observe("test.metric", [$host=1.2.3.4], [$num=51]);
+	SumStats::observe("test.metric", [$host=1.2.3.4], [$num=51]);
+	SumStats::observe("test.metric", [$host=1.2.3.4], [$num=51]);
+	SumStats::observe("test.metric", [$host=1.2.3.4], [$num=51]);
+	SumStats::observe("test.metric", [$host=1.2.3.4], [$num=51]);
+	SumStats::observe("test.metric", [$host=1.2.3.4], [$num=51]);
+	SumStats::observe("test.metric", [$host=1.2.3.4], [$num=51]);
+	SumStats::observe("test.metric", [$host=1.2.3.4], [$num=51]);
+	SumStats::observe("test.metric", [$host=1.2.3.4], [$num=51]);
+	SumStats::observe("test.metric", [$host=1.2.3.4], [$num=51]);
+	SumStats::observe("test.metric", [$host=1.2.3.4], [$num=51]);
+
+	SumStats::observe("test.metric", [$host=6.5.4.3], [$num=2]);
+	SumStats::observe("test.metric", [$host=7.2.1.5], [$num=1]);
+	}
+