diff --git a/datasets/decompress.sh b/datasets/decompress.sh
index 691df92..f95631e 100755
--- a/datasets/decompress.sh
+++ b/datasets/decompress.sh
@@ -1,8 +1,24 @@
 #!/bin/bash
 
-filenames=$( ls *.tar.xz )
+comm="new" # decompress only new files
 
-for filename in ${filenames[@]}; do
-	echo "Decompressing ${filename}"
-    tar -xJf "${filename}" 
+if [[ $# -eq 1 ]]; then
+	comm="$1"
+fi 
+
+echo $comm
+
+source_filenames=$( ls *.tar.xz )
+
+for source_filename in ${source_filenames[@]}; do
+	target_filename=$(basename $source_filename) 
+	target_filename="${target_filename%.*}" # remove .xz extension
+	target_filename=$(basename $target_filename)
+	target_filename="${target_filename%.*}" # remove .tar extension
+	if [ "$comm" == "all" ] || [ ! -f $target_filename ]; then
+		echo "Decompressing ${source_filename}"
+		tar -xJf "${source_filename}" 
+	else
+		echo "Skipping ${source_filename}"
+	fi
 done