diff --git a/.classpath b/.classpath
index 1dbc32b..35edb50 100644
--- a/.classpath
+++ b/.classpath
@@ -22,5 +22,6 @@
 	</classpathentry>
 	<classpathentry kind="lib" path="lib/mysql-jdbc-5.0.8.jar"/>
 	<classpathentry kind="lib" path="lib/devinsy-utils-0.2.6.jar"/>
+	<classpathentry kind="lib" path="lib/joda-time-2.3.jar" sourcepath="lib/joda-time-2.3-sources.jar"/>
 	<classpathentry kind="output" path="bin"/>
 </classpath>
diff --git a/bin/fr/devinsy/sikevadb/Element.class b/bin/fr/devinsy/sikevadb/Element.class
index c1f8954..a831e1a 100644
Binary files a/bin/fr/devinsy/sikevadb/Element.class and b/bin/fr/devinsy/sikevadb/Element.class differ
diff --git a/bin/fr/devinsy/sikevadb/FileSikevaDB.class b/bin/fr/devinsy/sikevadb/FileSikevaDB.class
index d66033d..2028a3d 100644
Binary files a/bin/fr/devinsy/sikevadb/FileSikevaDB.class and b/bin/fr/devinsy/sikevadb/FileSikevaDB.class differ
diff --git a/bin/fr/devinsy/sikevadb/SQLSikevaDB.class b/bin/fr/devinsy/sikevadb/SQLSikevaDB.class
index 8e3c2c8..92bdb17 100644
Binary files a/bin/fr/devinsy/sikevadb/SQLSikevaDB.class and b/bin/fr/devinsy/sikevadb/SQLSikevaDB.class differ
diff --git a/bin/fr/devinsy/sikevadb/SikevaDB.class b/bin/fr/devinsy/sikevadb/SikevaDB.class
index 9edca4e..7862bbb 100644
Binary files a/bin/fr/devinsy/sikevadb/SikevaDB.class and b/bin/fr/devinsy/sikevadb/SikevaDB.class differ
diff --git a/lib/joda-time-2.3-sources.jar b/lib/joda-time-2.3-sources.jar
new file mode 100644
index 0000000..a2dda2e
Binary files /dev/null and b/lib/joda-time-2.3-sources.jar differ
diff --git a/lib/joda-time-2.3.jar b/lib/joda-time-2.3.jar
new file mode 100644
index 0000000..9dce4f9
Binary files /dev/null and b/lib/joda-time-2.3.jar differ
diff --git a/src/fr/devinsy/sikevadb/Element.java b/src/fr/devinsy/sikevadb/Element.java
index 21f5adf..2d6ad4c 100644
--- a/src/fr/devinsy/sikevadb/Element.java
+++ b/src/fr/devinsy/sikevadb/Element.java
@@ -15,9 +15,8 @@
  */
 package fr.devinsy.sikevadb;
 
-import java.util.Date;
-
 import org.apache.commons.codec.digest.DigestUtils;
+import org.joda.time.DateTime;
 
 /**
  * 
@@ -26,9 +25,9 @@ import org.apache.commons.codec.digest.DigestUtils;
  */
 public class Element {
 
-	private Date creationDate;
-	private Date editionDate;
-	private Date archiveDate;
+	private DateTime creationDate;
+	private DateTime editionDate;
+	private DateTime archiveDate;
 	private String key;
 	private String subkey;
 	private long size;
@@ -59,14 +58,14 @@ public class Element {
 	 * 
 	 */
 	public void archive() {
-		this.archiveDate = new Date();
+		this.archiveDate = DateTime.now();
 	}
 
-	public Date getArchiveDate() {
+	public DateTime getArchiveDate() {
 		return archiveDate;
 	}
 
-	public Date getCreationDate() {
+	public DateTime getCreationDate() {
 		return creationDate;
 	}
 
@@ -74,7 +73,7 @@ public class Element {
 		return digest;
 	}
 
-	public Date getEditionDate() {
+	public DateTime getEditionDate() {
 		return editionDate;
 	}
 
@@ -94,24 +93,20 @@ public class Element {
 		return value;
 	}
 
-	public void setArchiveDate(final Date archiveDate) {
-		if (archiveDate == null) {
-			this.archiveDate = null;
-		} else {
-			this.archiveDate = (Date) archiveDate.clone();
-		}
+	public void setArchiveDate(final DateTime date) {
+		this.archiveDate = date;
 	}
 
-	public void setCreationDate(final Date creationDate) {
-		this.creationDate = (Date) creationDate.clone();
+	public void setCreationDate(final DateTime date) {
+		this.creationDate = date;
 	}
 
 	public void setDigest(final String digest) {
 		this.digest = digest;
 	}
 
-	public void setEditionDate(final Date editionDate) {
-		this.editionDate = (Date) editionDate.clone();
+	public void setEditionDate(final DateTime date) {
+		this.editionDate = date;
 	}
 
 	public void setKey(final String key) {
@@ -135,7 +130,7 @@ public class Element {
 		setValue(value);
 
 		//
-		this.editionDate = new Date();
+		this.editionDate = DateTime.now();
 
 		//
 		if (value == null) {
diff --git a/src/fr/devinsy/sikevadb/FileSikevaDB.java b/src/fr/devinsy/sikevadb/FileSikevaDB.java
index d493560..b946eb2 100644
--- a/src/fr/devinsy/sikevadb/FileSikevaDB.java
+++ b/src/fr/devinsy/sikevadb/FileSikevaDB.java
@@ -16,7 +16,8 @@
 package fr.devinsy.sikevadb;
 
 import java.io.File;
-import java.util.Date;
+
+import org.joda.time.DateTime;
 
 import fr.devinsy.util.StringList;
 
@@ -61,7 +62,7 @@ public class FileSikevaDB implements SikevaDB {
 	}
 
 	@Override
-	public void clearArchive(final Date beforeDate) throws Exception {
+	public void clearArchive(final DateTime beforeDate) throws Exception {
 		// TODO Auto-generated method stub
 
 	}
diff --git a/src/fr/devinsy/sikevadb/SQLSikevaDB.java b/src/fr/devinsy/sikevadb/SQLSikevaDB.java
index f61e883..62dbd4c 100644
--- a/src/fr/devinsy/sikevadb/SQLSikevaDB.java
+++ b/src/fr/devinsy/sikevadb/SQLSikevaDB.java
@@ -29,6 +29,7 @@ import javax.naming.NamingException;
 import javax.sql.DataSource;
 
 import org.apache.commons.lang3.StringUtils;
+import org.joda.time.DateTime;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -107,7 +108,7 @@ public class SQLSikevaDB implements SikevaDB {
 				connection.setAutoCommit(true);
 				statement = connection.prepareStatement("UPDATE elements SET ARCHIVE_DATE=? WHERE TOPKEY=? AND SUBKEY IS NULL");
 
-				statement.setTimestamp(1, dateToTimestamp(element.getArchiveDate()));
+				statement.setTimestamp(1, toTimestamp(element.getArchiveDate()));
 				statement.setString(2, element.getKey());
 
 				statement.executeUpdate();
@@ -146,7 +147,7 @@ public class SQLSikevaDB implements SikevaDB {
 					connection.setAutoCommit(true);
 					statement = connection.prepareStatement("UPDATE elements SET ARCHIVE_DATE=? WHERE TOPKEY=? AND SUBKEY=?");
 
-					statement.setTimestamp(1, dateToTimestamp(element.getArchiveDate()));
+					statement.setTimestamp(1, toTimestamp(element.getArchiveDate()));
 					statement.setString(2, element.getKey());
 					statement.setString(3, element.getSubkey());
 
@@ -185,7 +186,7 @@ public class SQLSikevaDB implements SikevaDB {
 	 * {@inheritDoc}
 	 */
 	@Override
-	public void clearArchive(final Date beforeDate) throws SQLException {
+	public void clearArchive(final DateTime beforeDate) throws SQLException {
 		//
 		if (beforeDate == null) {
 			throw new NullPointerException("beforeDate is null.");
@@ -198,9 +199,9 @@ public class SQLSikevaDB implements SikevaDB {
 				//
 				connection = getConnection();
 				connection.setAutoCommit(true);
-				statement = connection.prepareStatement("DELETE FROM elements WHERE ARCHIVE_DATE IS NOT NULL AND TO_SECONDS(ARCHIVE_DATE)<?");
+				statement = connection.prepareStatement("DELETE FROM elements WHERE ARCHIVE_DATE IS NOT NULL AND UNIX_TIMESTAMP(ARCHIVE_DATE)<?");
 
-				statement.setLong(1, beforeDate.getTime() / 1000);
+				statement.setLong(1, beforeDate.getMillis() / 1000);
 
 				statement.executeUpdate();
 
@@ -222,7 +223,7 @@ public class SQLSikevaDB implements SikevaDB {
 		if (maxDays < 0) {
 			throw new IndexOutOfBoundsException("maxDays is negative.");
 		} else {
-			Date beforeDate = new Date(new Date().getTime() - maxDays * 24 * 60 * 60 * 1000);
+			DateTime beforeDate = DateTime.now().minusDays(maxDays);
 			clearArchive(beforeDate);
 		}
 	}
@@ -603,9 +604,9 @@ public class SQLSikevaDB implements SikevaDB {
 				element.setValue(resultSet.getString(3));
 				element.setSize(resultSet.getLong(4));
 				element.setDigest(resultSet.getString(5));
-				element.setCreationDate(timestampToDate(resultSet.getTimestamp(6)));
-				element.setEditionDate(timestampToDate(resultSet.getTimestamp(7)));
-				element.setArchiveDate(timestampToDate(resultSet.getTimestamp(8)));
+				element.setCreationDate(toDateTime(resultSet.getTimestamp(6)));
+				element.setEditionDate(toDateTime(resultSet.getTimestamp(7)));
+				element.setArchiveDate(toDateTime(resultSet.getTimestamp(8)));
 
 				//
 				result.add(element);
@@ -654,9 +655,9 @@ public class SQLSikevaDB implements SikevaDB {
 					element.setValue(resultSet.getString(3));
 					element.setSize(resultSet.getLong(4));
 					element.setDigest(resultSet.getString(5));
-					element.setCreationDate(timestampToDate(resultSet.getTimestamp(6)));
-					element.setEditionDate(timestampToDate(resultSet.getTimestamp(7)));
-					element.setArchiveDate(timestampToDate(resultSet.getTimestamp(8)));
+					element.setCreationDate(toDateTime(resultSet.getTimestamp(6)));
+					element.setEditionDate(toDateTime(resultSet.getTimestamp(7)));
+					element.setArchiveDate(toDateTime(resultSet.getTimestamp(8)));
 
 					//
 					result.add(element);
@@ -948,9 +949,9 @@ public class SQLSikevaDB implements SikevaDB {
 				result.setValue(resultSet.getString(3));
 				result.setSize(resultSet.getLong(4));
 				result.setDigest(resultSet.getString(5));
-				result.setCreationDate(timestampToDate(resultSet.getTimestamp(6)));
-				result.setEditionDate(timestampToDate(resultSet.getTimestamp(7)));
-				result.setArchiveDate(timestampToDate(resultSet.getTimestamp(8)));
+				result.setCreationDate(toDateTime(resultSet.getTimestamp(6)));
+				result.setEditionDate(toDateTime(resultSet.getTimestamp(7)));
+				result.setArchiveDate(toDateTime(resultSet.getTimestamp(8)));
 
 			} else {
 				result = null;
@@ -1003,9 +1004,9 @@ public class SQLSikevaDB implements SikevaDB {
 					result.setValue(resultSet.getString(3));
 					result.setSize(resultSet.getLong(4));
 					result.setDigest(resultSet.getString(5));
-					result.setCreationDate(timestampToDate(resultSet.getTimestamp(6)));
-					result.setEditionDate(timestampToDate(resultSet.getTimestamp(7)));
-					result.setArchiveDate(timestampToDate(resultSet.getTimestamp(8)));
+					result.setCreationDate(toDateTime(resultSet.getTimestamp(6)));
+					result.setEditionDate(toDateTime(resultSet.getTimestamp(7)));
+					result.setArchiveDate(toDateTime(resultSet.getTimestamp(8)));
 				} else {
 					result = null;
 				}
@@ -1054,9 +1055,9 @@ public class SQLSikevaDB implements SikevaDB {
 				element.setValue(resultSet.getString(3));
 				element.setSize(resultSet.getLong(4));
 				element.setDigest(resultSet.getString(5));
-				element.setCreationDate(timestampToDate(resultSet.getTimestamp(6)));
-				element.setEditionDate(timestampToDate(resultSet.getTimestamp(7)));
-				element.setArchiveDate(timestampToDate(resultSet.getTimestamp(8)));
+				element.setCreationDate(toDateTime(resultSet.getTimestamp(6)));
+				element.setEditionDate(toDateTime(resultSet.getTimestamp(7)));
+				element.setArchiveDate(toDateTime(resultSet.getTimestamp(8)));
 
 				//
 				result.add(element);
@@ -1105,9 +1106,9 @@ public class SQLSikevaDB implements SikevaDB {
 					element.setValue(resultSet.getString(3));
 					element.setSize(resultSet.getLong(4));
 					element.setDigest(resultSet.getString(5));
-					element.setCreationDate(timestampToDate(resultSet.getTimestamp(6)));
-					element.setEditionDate(timestampToDate(resultSet.getTimestamp(7)));
-					element.setArchiveDate(timestampToDate(resultSet.getTimestamp(8)));
+					element.setCreationDate(toDateTime(resultSet.getTimestamp(6)));
+					element.setEditionDate(toDateTime(resultSet.getTimestamp(7)));
+					element.setArchiveDate(toDateTime(resultSet.getTimestamp(8)));
 
 					//
 					result.add(element);
@@ -1619,9 +1620,9 @@ public class SQLSikevaDB implements SikevaDB {
 			statement.setString(3, element.getValue());
 			statement.setLong(4, element.getSize());
 			statement.setString(5, element.getDigest());
-			statement.setTimestamp(6, new java.sql.Timestamp(element.getCreationDate().getTime()));
-			statement.setTimestamp(7, dateToTimestamp(element.getEditionDate()));
-			statement.setTimestamp(8, dateToTimestamp(element.getArchiveDate()));
+			statement.setTimestamp(6, toTimestamp(element.getCreationDate()));
+			statement.setTimestamp(7, toTimestamp(element.getEditionDate()));
+			statement.setTimestamp(8, toTimestamp(element.getArchiveDate()));
 
 			statement.executeUpdate();
 
@@ -1663,7 +1664,7 @@ public class SQLSikevaDB implements SikevaDB {
 				// Archive existing element.
 				statement = connection.prepareStatement("UPDATE elements SET ARCHIVE_DATE=? WHERE TOPKEY=? AND SUBKEY IS NULL");
 
-				statement.setTimestamp(1, dateToTimestamp(element.getEditionDate()));
+				statement.setTimestamp(1, toTimestamp(element.getEditionDate()));
 				statement.setString(2, element.getKey());
 
 				statement.executeUpdate();
@@ -1679,9 +1680,9 @@ public class SQLSikevaDB implements SikevaDB {
 				statement.setString(3, element.getValue());
 				statement.setLong(4, element.getSize());
 				statement.setString(5, element.getDigest());
-				statement.setTimestamp(6, dateToTimestamp(element.getCreationDate()));
-				statement.setTimestamp(7, dateToTimestamp(element.getEditionDate()));
-				statement.setTimestamp(8, dateToTimestamp(element.getArchiveDate()));
+				statement.setTimestamp(6, toTimestamp(element.getCreationDate()));
+				statement.setTimestamp(7, toTimestamp(element.getEditionDate()));
+				statement.setTimestamp(8, toTimestamp(element.getArchiveDate()));
 
 				statement.executeUpdate();
 
@@ -1732,7 +1733,7 @@ public class SQLSikevaDB implements SikevaDB {
 				// Archive existing element.
 				statement = connection.prepareStatement("UPDATE elements SET ARCHIVE_DATE=? WHERE TOPKEY=? AND SUBKEY=?");
 
-				statement.setTimestamp(1, dateToTimestamp(element.getEditionDate()));
+				statement.setTimestamp(1, toTimestamp(element.getEditionDate()));
 				statement.setString(2, element.getKey());
 				statement.setString(3, element.getSubkey());
 
@@ -1749,9 +1750,9 @@ public class SQLSikevaDB implements SikevaDB {
 				statement.setString(3, element.getValue());
 				statement.setLong(4, element.getSize());
 				statement.setString(5, element.getDigest());
-				statement.setTimestamp(6, dateToTimestamp(element.getCreationDate()));
-				statement.setTimestamp(7, dateToTimestamp(element.getEditionDate()));
-				statement.setTimestamp(8, dateToTimestamp(element.getArchiveDate()));
+				statement.setTimestamp(6, toTimestamp(element.getCreationDate()));
+				statement.setTimestamp(7, toTimestamp(element.getEditionDate()));
+				statement.setTimestamp(8, toTimestamp(element.getArchiveDate()));
 
 				statement.executeUpdate();
 
@@ -1888,7 +1889,25 @@ public class SQLSikevaDB implements SikevaDB {
 	 * @param source
 	 * @return
 	 */
-	public static java.sql.Timestamp dateToTimestamp(final Date source) {
+	public static DateTime toDateTime(final java.sql.Timestamp source) {
+		DateTime result;
+
+		if (source == null) {
+			result = null;
+		} else {
+			result = new DateTime(source.getTime());
+		}
+
+		//
+		return result;
+	}
+
+	/**
+	 * 
+	 * @param source
+	 * @return
+	 */
+	public static java.sql.Timestamp toTimestamp(final Date source) {
 		java.sql.Timestamp result;
 
 		if (source == null) {
@@ -1906,13 +1925,13 @@ public class SQLSikevaDB implements SikevaDB {
 	 * @param source
 	 * @return
 	 */
-	public static Date timestampToDate(final java.sql.Timestamp source) {
-		Date result;
+	public static java.sql.Timestamp toTimestamp(final DateTime source) {
+		java.sql.Timestamp result;
 
 		if (source == null) {
 			result = null;
 		} else {
-			result = new Date(source.getTime());
+			result = new java.sql.Timestamp(source.getMillis());
 		}
 
 		//
diff --git a/src/fr/devinsy/sikevadb/SikevaDB.java b/src/fr/devinsy/sikevadb/SikevaDB.java
index 360fb09..37348e3 100644
--- a/src/fr/devinsy/sikevadb/SikevaDB.java
+++ b/src/fr/devinsy/sikevadb/SikevaDB.java
@@ -15,7 +15,7 @@
  */
 package fr.devinsy.sikevadb;
 
-import java.util.Date;
+import org.joda.time.DateTime;
 
 import fr.devinsy.util.StringList;
 
@@ -34,7 +34,7 @@ public interface SikevaDB {
 
 	public void clearAllArchive() throws Exception;
 
-	public void clearArchive(final Date beforeDate) throws Exception;
+	public void clearArchive(final DateTime beforeDate) throws Exception;
 
 	public void clearArchive(final int maxDays) throws Exception;
 
diff --git a/src/fr/devinsy/sikevadb/XMLSikevaDB.java b/src/fr/devinsy/sikevadb/XMLSikevaDB.java
index 7c4d201..9dfe957 100644
--- a/src/fr/devinsy/sikevadb/XMLSikevaDB.java
+++ b/src/fr/devinsy/sikevadb/XMLSikevaDB.java
@@ -2,11 +2,11 @@ package fr.devinsy.sikevadb;
 
 import java.io.File;
 import java.io.OutputStream;
-import java.util.Date;
 
 import javax.xml.stream.XMLStreamException;
 
 import org.apache.commons.lang3.StringEscapeUtils;
+import org.joda.time.DateTime;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -93,15 +93,15 @@ public class XMLSikevaDB {
 			String value = StringEscapeUtils.unescapeXml(in.readContentTag("value").getContent());
 			int size = Integer.parseInt(tag.attributes().getByLabel("size").getValue());
 			String digest = in.readContentTag("digest").getContent();
-			Date creationDate = new Date(Long.parseLong(in.readContentTag("creation_date").getContent()));
-			Date editionDate = new Date(Long.parseLong(in.readContentTag("edition_date").getContent()));
+			DateTime creationDate = DateTime.parse(in.readContentTag("creation_date").getContent());
+			DateTime editionDate = DateTime.parse(in.readContentTag("edition_date").getContent());
 
-			Date archiveDate;
+			DateTime archiveDate;
 			String archiveDateValue = in.readNullableContentTag("archive_date").getContent();
 			if (archiveDateValue == null) {
 				archiveDate = null;
 			} else {
-				archiveDate = new Date(Long.parseLong(archiveDateValue));
+				archiveDate = DateTime.parse(archiveDateValue);
 			}
 
 			//
@@ -178,12 +178,12 @@ public class XMLSikevaDB {
 				out.writeTag("value", StringEscapeUtils.escapeXml(source.getValue()));
 				out.writeTag("size", String.valueOf(source.getSize()));
 				out.writeTag("digest", source.getDigest());
-				out.writeTag("creation_date", String.valueOf(source.getCreationDate().getTime()));
-				out.writeTag("edition_date", String.valueOf(source.getEditionDate().getTime()));
+				out.writeTag("creation_date", source.getCreationDate().toString());
+				out.writeTag("edition_date", source.getEditionDate().toString());
 				if (source.getArchiveDate() == null) {
 					out.writeTag("archive_date", null);
 				} else {
-					out.writeTag("archive_date", String.valueOf(source.getArchiveDate().getTime()));
+					out.writeTag("archive_date", source.getArchiveDate().toString());
 				}
 			}
 
diff --git a/test/fr/devinsy/sikevadb/SQLSikevaDBTest.java b/test/fr/devinsy/sikevadb/SQLSikevaDBTest.java
index 0a9e61f..03c0323 100644
--- a/test/fr/devinsy/sikevadb/SQLSikevaDBTest.java
+++ b/test/fr/devinsy/sikevadb/SQLSikevaDBTest.java
@@ -1,7 +1,6 @@
 package fr.devinsy.sikevadb;
 
 import java.sql.SQLException;
-import java.util.Date;
 
 import javax.naming.NamingException;
 
@@ -10,6 +9,7 @@ import org.apache.commons.lang3.RandomStringUtils;
 import org.apache.log4j.BasicConfigurator;
 import org.apache.log4j.Level;
 import org.apache.log4j.Logger;
+import org.joda.time.DateTime;
 import org.junit.After;
 import org.junit.Assert;
 import org.junit.Before;
@@ -70,9 +70,9 @@ public class SQLSikevaDBTest {
 		element.setSubkey(null);
 		element.setSize(10);
 		element.setDigest("qsdkfqskjf");
-		element.setCreationDate(new Date());
-		element.setEditionDate(new Date());
-		element.setArchiveDate(new Date(new Date().getTime() - 10 * 24 * 60 * 60 * 1000));
+		element.setCreationDate(DateTime.now().minusDays(11));
+		element.setEditionDate(DateTime.now().minusDays(11));
+		element.setArchiveDate(DateTime.now().minusDays(10));
 		element.setValue("bonjour");
 
 		database.put(element);
@@ -106,16 +106,16 @@ public class SQLSikevaDBTest {
 		element.setSubkey(null);
 		element.setSize(10);
 		element.setDigest("qsdkfqskjf");
-		element.setCreationDate(new Date());
-		element.setEditionDate(new Date());
-		element.setArchiveDate(new Date(new Date().getTime() - 10 * 24 * 60 * 60 * 1000));
+		element.setCreationDate(DateTime.now());
+		element.setEditionDate(DateTime.now());
+		element.setArchiveDate(DateTime.now().minusDays(10));
 		element.setValue("bonjour");
 
 		database.put(element);
 
 		database.put("alpha", "bravo", "toto");
 
-		database.clearArchive(new Date(new Date().getTime() - 5 * 24 * 60 * 60 * 1000));
+		database.clearArchive(DateTime.now().minusDays(5));
 
 		Assert.assertEquals(1, database.countOfElements());
 		Assert.assertEquals(0, database.countOfArchivedElements());
@@ -216,7 +216,8 @@ public class SQLSikevaDBTest {
 		database.put("alpha01", "bravo5", "qlskjfmlqj");
 
 		Assert.assertEquals(120, database.memorySize());
-		Assert.assertEquals(10, database.memorySize("alpha01"));
+		Assert.assertEquals(60, database.memorySize("alpha01"));
+		Assert.assertEquals(10, database.memorySize("alpha03"));
 		Assert.assertEquals(10, database.memorySize("alpha01", "bravo1"));
 
 		database.clearDatabase();