diff --git a/data-store/src/main/java/org/lucares/pdb/datastore/internal/DataStore.java b/data-store/src/main/java/org/lucares/pdb/datastore/internal/DataStore.java
index a4facf4..f1414bb 100644
--- a/data-store/src/main/java/org/lucares/pdb/datastore/internal/DataStore.java
+++ b/data-store/src/main/java/org/lucares/pdb/datastore/internal/DataStore.java
@@ -27,6 +27,7 @@ import org.slf4j.LoggerFactory;
 
 public class DataStore {
 	private static final Logger EXECUTE_QUERY_LOGGER = LoggerFactory.getLogger("org.lucares.metrics.dataStore.executeQuery");
+	private static final Logger LOGGER = LoggerFactory.getLogger(DataStore.class);
 
 	private static final String SUBDIR_STORAGE = "storage";
 	private static final String PDB_EXTENSION = ".pdb";
@@ -68,6 +69,7 @@ public class DataStore {
 			cacheTagToFileMapping(tags, path);
 
 		});
+		trimIntLists();
 	}
 
 	private void cacheTagToFileMapping(final Tags tags, final Path path) {
@@ -85,6 +87,30 @@ public class DataStore {
 		}
 	}
 
+	private void trimIntLists() {
+		final long start = System.nanoTime();
+		int totalBeforeTrim = 0;
+		int totalAfterTrim = 0;
+		int totalValues = 0;
+		for (Map<String, IntList> valueToDocIds : keyToValueToDocId.values()) {
+			
+			for (IntList intList : valueToDocIds.values()) {
+				totalBeforeTrim += intList.getCapacity();
+				intList.trim();
+				totalAfterTrim += intList.getCapacity();
+				totalValues += intList.size();
+			}
+		}
+		
+		LOGGER.info(
+				"trimming IntLists of index: values {}, {} kB before, {} kB after, difference {} kB, total size: {} kB, took: {} ms",
+				totalValues,
+				(totalBeforeTrim * 4) / 1024, (totalAfterTrim * 4) / 1024,
+				((totalBeforeTrim - totalAfterTrim) * 4) / 1024,
+				(totalValues * 4) / 1024,
+				(System.nanoTime() - start) / 1_000_000.0);
+	}
+
 	private Path keyCompressionFile(final Path dataDirectory) throws IOException {
 		return dataDirectory.resolve("keys.csv");
 	}