diff --git a/src/main/java/org/gcube/accounting/analytics/ResourceRecordQuery.java b/src/main/java/org/gcube/accounting/analytics/ResourceRecordQuery.java
index c183975..372b04b 100644
--- a/src/main/java/org/gcube/accounting/analytics/ResourceRecordQuery.java
+++ b/src/main/java/org/gcube/accounting/analytics/ResourceRecordQuery.java
@@ -173,4 +173,11 @@ public class ResourceRecordQuery {
 		return toSort;
 	}
 	
+	public List<String> getPossibleValuesForKey(@SuppressWarnings("rawtypes") Class<? extends AggregatedUsageRecord> usageRecordType, String key) throws Exception {
+		Set<String> keys = accountingPersistenceQuery.getPossibleValuesForKey(usageRecordType, key);
+		List<String> toSort = new ArrayList<String>(keys);
+		Collections.sort(toSort);
+		return toSort;
+	}
+	
 }
diff --git a/src/main/java/org/gcube/accounting/analytics/persistence/AccountingPersistenceQuery.java b/src/main/java/org/gcube/accounting/analytics/persistence/AccountingPersistenceQuery.java
index 08cd31f..5dcfe49 100644
--- a/src/main/java/org/gcube/accounting/analytics/persistence/AccountingPersistenceQuery.java
+++ b/src/main/java/org/gcube/accounting/analytics/persistence/AccountingPersistenceQuery.java
@@ -57,9 +57,20 @@ public abstract class AccountingPersistenceQuery {
 	 */
 	public abstract Set<String> getKeys(@SuppressWarnings("rawtypes") Class<? extends AggregatedUsageRecord> usageRecordType) throws Exception;
 	
+	
+	/**
+	 * Return the list of possible values for a key for a certain usage record type
+	 * @param usageRecordType the usage record type 
+	 * @param key the key 
+	 * @return a set containing the list of possible values
+	 * @throws Exception if fails
+	 */
+	public abstract Set<String> getPossibleValuesForKey(@SuppressWarnings("rawtypes") Class<? extends AggregatedUsageRecord> usageRecordType, String key) throws Exception;
+	
 	/**
 	 * Close the connection to persistence
 	 * @throws Exception if the close fails
 	 */
 	public abstract void close() throws Exception;
+	
 }