diff --git a/avocado-core/src/main/scala/org/bdgenomics/avocado/discovery/ReassemblyExplorer.scala b/avocado-core/src/main/scala/org/bdgenomics/avocado/discovery/ReassemblyExplorer.scala
index 37eb7a19..c67503c5 100644
--- a/avocado-core/src/main/scala/org/bdgenomics/avocado/discovery/ReassemblyExplorer.scala
+++ b/avocado-core/src/main/scala/org/bdgenomics/avocado/discovery/ReassemblyExplorer.scala
@@ -21,8 +21,8 @@ import org.apache.commons.configuration.{ HierarchicalConfiguration, SubnodeConf
 import org.apache.spark.SparkContext._
 import org.apache.spark.Logging
 import org.apache.spark.rdd.RDD
-import org.bdgenomics.adam.models.{ ReferenceMapping, ReferenceRegion }
-import org.bdgenomics.adam.rdd.RegionJoin
+import org.bdgenomics.adam.models.{ ReferenceMapping, ReferenceRegion, SequenceDictionary }
+import org.bdgenomics.adam.rdd.ShuffleRegionJoin
 import org.bdgenomics.adam.rich.ReferenceMappingContext._
 import org.bdgenomics.avocado.algorithms.debrujin.KmerGraph
 import org.bdgenomics.avocado.models.{ Observation }
@@ -36,7 +36,7 @@ object ReassemblyExplorer extends ExplorerCompanion {
   protected def apply(stats: AvocadoConfigAndStats,
                       config: SubnodeConfiguration): Explorer = {
     val kmerLength = config.getInt("kmerLength", 20)
-    new ReassemblyExplorer(kmerLength, stats.reference)
+    new ReassemblyExplorer(kmerLength, stats.reference, stats.sequenceDict, stats.contigLengths)
   }
 
   implicit object ContigReferenceMapping extends ReferenceMapping[(Long, NucleotideContigFragment)] with Serializable {
@@ -48,7 +48,11 @@ object ReassemblyExplorer extends ExplorerCompanion {
 import ReassemblyExplorer._
 
 class ReassemblyExplorer(kmerLength: Int,
-                         reference: RDD[NucleotideContigFragment]) extends Explorer with Logging {
+                         reference: RDD[NucleotideContigFragment],
+                         sd: SequenceDictionary,
+                         contigLengths: Map[String, Long]) extends Explorer with Logging {
+
+  val totalAssembledReferenceLength = contigLengths.values.sum
 
   val companion: ExplorerCompanion = ReassemblyExplorer
 
@@ -76,9 +80,11 @@ class ReassemblyExplorer(kmerLength: Int,
     // filter mapped reads, join with reference contigs, then extract contig ids
     // ultimately, this should use the merge-sort join, not the broadcast join
     // will upgrade when ADAM-534 merges.
-    val joinWithId = RegionJoin.partitionAndJoin(reference.context,
+    val joinWithId = ShuffleRegionJoin.partitionAndJoin(reference.context,
       refIds,
-      reads.filter(_.getReadMapped))
+      reads.filter(_.getReadMapped),
+      sd,
+      totalAssembledReferenceLength / reads.partitions.size)
       .map(kv => {
         (kv._1._1, kv._2)
       })
diff --git a/avocado-core/src/main/scala/org/bdgenomics/avocado/genotyping/ExternalGenotyper.scala b/avocado-core/src/main/scala/org/bdgenomics/avocado/genotyping/ExternalGenotyper.scala
index a2ca1374..f329d279 100644
--- a/avocado-core/src/main/scala/org/bdgenomics/avocado/genotyping/ExternalGenotyper.scala
+++ b/avocado-core/src/main/scala/org/bdgenomics/avocado/genotyping/ExternalGenotyper.scala
@@ -30,7 +30,7 @@ import org.bdgenomics.formats.avro.AlignmentRecord
 import org.bdgenomics.adam.converters.VariantContextConverter
 import org.bdgenomics.adam.models.{ SAMFileHeaderWritable, VariantContext => ADAMVariantContext, ReferencePosition }
 import org.bdgenomics.adam.rdd.ADAMContext._
-import org.bdgenomics.adam.rdd.GenomicRegionPartitioner
+import org.bdgenomics.adam.rdd.GenomicPositionPartitioner
 import org.bdgenomics.adam.rdd.read.AlignmentRecordContext._
 import org.bdgenomics.avocado.models.{ Observation, ReadObservation }
 import org.bdgenomics.avocado.stats.AvocadoConfigAndStats
@@ -199,7 +199,7 @@ class ExternalGenotyper(contigLengths: Map[String, Long],
 
     // key reads by position and repartition
     val readsByPosition = reads.keyBy(r => ReferencePosition(r.get.getReferenceName.toString, r.get.getAlignmentStart))
-      .partitionBy(new GenomicRegionPartitioner(numPart, contigLengths))
+      .partitionBy(GenomicPositionPartitioner(numPart, contigLengths))
 
     if (debug) {
       log.info("have " + readsByPosition.count + " reads after partitioning")
diff --git a/avocado-core/src/test/scala/org/bdgenomics/avocado/discovery/ReassemblyExplorerSuite.scala b/avocado-core/src/test/scala/org/bdgenomics/avocado/discovery/ReassemblyExplorerSuite.scala
index 90f7de21..3381aa8a 100644
--- a/avocado-core/src/test/scala/org/bdgenomics/avocado/discovery/ReassemblyExplorerSuite.scala
+++ b/avocado-core/src/test/scala/org/bdgenomics/avocado/discovery/ReassemblyExplorerSuite.scala
@@ -21,6 +21,7 @@ import org.apache.spark.rdd.RDD
 import org.apache.spark.SparkContext._
 import org.bdgenomics.adam.models.ReferenceRegion
 import org.bdgenomics.adam.rdd.ADAMContext._
+import org.bdgenomics.adam.rdd.read.AlignmentRecordRDDFunctions
 import org.bdgenomics.adam.rich.RichGenotype._
 import org.bdgenomics.adam.rich.{ RichAlignmentRecord, RichGenotype }
 import org.bdgenomics.adam.util.SparkFunSuite
@@ -85,12 +86,15 @@ class ReassemblyExplorerSuite extends SparkFunSuite {
     sc.loadAlignments(path)
   }
 
+  lazy val sd = new AlignmentRecordRDDFunctions(na12878_chr20_snp_reads).adamGetSequenceDictionary()
+  lazy val cl = sd.records.map(r => (r.name, r.length)).toMap
+
   sparkTest("reassemble and call variants on real data") {
     val reads = na12878_chr20_snp_reads
 
     val reference = getReferenceFromReads(reads.collect.toSeq)
 
-    val re = new ReassemblyExplorer(20, sc.parallelize(Seq(reference)))
+    val re = new ReassemblyExplorer(20, sc.parallelize(Seq(reference)), sd, cl)
     val obs = re.discover(reads)
     val bg = new BiallelicGenotyper()
     val vc = bg.genotype(obs)
@@ -110,7 +114,7 @@ class ReassemblyExplorerSuite extends SparkFunSuite {
 
     val reference = getReferenceFromReads(reads.collect.toSeq)
 
-    val re = new ReassemblyExplorer(20, sc.parallelize(Seq(reference)))
+    val re = new ReassemblyExplorer(20, sc.parallelize(Seq(reference)), sd, cl)
     val obs = re.discover(reads)
     val bg = new BiallelicGenotyper()
     val vc = bg.genotype(obs)
diff --git a/pom.xml b/pom.xml
index 21da1300..ad45d12f 100644
--- a/pom.xml
+++ b/pom.xml
@@ -20,7 +20,7 @@
     <java.version>1.7</java.version>
     <scala.version>2.10.3</scala.version>
     <scala.version.prefix>2.10</scala.version.prefix>
-    <spark.version>1.1.0</spark.version>
+    <spark.version>1.2.0</spark.version>
     <!-- Edit the following line to configure the Hadoop (HDFS) version. -->
     <hadoop.version>2.2.0</hadoop.version>
   </properties>
@@ -238,6 +238,10 @@
         <artifactId>hadoop-client</artifactId>
         <version>${hadoop.version}</version>
         <exclusions>
+          <exclusion>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+          </exclusion>
           <exclusion>
             <groupId>asm</groupId>
             <artifactId>asm</artifactId>