diff -r 9f9b454eb77f src/org/openbravo/retail/posterminal/POSUtils.java
--- a/src/org/openbravo/retail/posterminal/POSUtils.java	Tue Dec 11 17:27:05 2012 +0100
+++ b/src/org/openbravo/retail/posterminal/POSUtils.java	Wed Dec 12 15:49:24 2012 +0100
@@ -1,21 +1,23 @@
 package org.openbravo.retail.posterminal;
 
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
 import java.util.ArrayList;
 import java.util.List;
 
 import org.apache.log4j.Logger;
-import org.hibernate.ScrollMode;
-import org.hibernate.ScrollableResults;
 import org.openbravo.base.exception.OBException;
+import org.openbravo.base.session.OBPropertiesProvider;
 import org.openbravo.client.kernel.KernelUtils;
 import org.openbravo.dal.core.OBContext;
 import org.openbravo.dal.service.OBCriteria;
 import org.openbravo.dal.service.OBDal;
 import org.openbravo.dal.service.OBQuery;
+import org.openbravo.database.ConnectionProviderImpl;
 import org.openbravo.model.ad.module.Module;
 import org.openbravo.model.ad.module.ModuleDependency;
 import org.openbravo.model.common.enterprise.Organization;
-import org.openbravo.model.common.order.Order;
 import org.openbravo.model.pricing.pricelist.PriceList;
 import org.openbravo.retail.config.OBRETCOProductList;
 
@@ -187,36 +189,57 @@
   }
 
   public static int getLastDocumentNumberForPOS(String searchKey, String documentTypeId) {
-    OBPOSApplications POSTerminal = POSUtils.getTerminal(searchKey);
+    String curDbms = OBPropertiesProvider.getInstance().getOpenbravoProperties()
+        .getProperty("bbdd.rdbms");
+    String sqlToExecute;
 
-    OBQuery<Order> obqOrders = OBDal.getInstance().createQuery(Order.class,
-        "em_obpos_applications_id = :value and documentType.id=:documentTypeId");
-    obqOrders.setNamedParameter("value", POSTerminal.getId());
-    obqOrders.setNamedParameter("documentTypeId", documentTypeId);
+    if (curDbms.equals("POSTGRE")) {
+      sqlToExecute = "select max(a.docno) from (select to_number(substring(documentno, '/([0-9]+)$')) docno from c_order where documentno like (select orderdocno_prefix || '/%' from obpos_applications where value = '"
+          + searchKey + "') and c_doctype_id = '" + documentTypeId + "' ) a";
+    } else if (curDbms.equals("ORACLE")) {
+      sqlToExecute = "select max(a.docno) from (select to_number(substr(REGEXP_SUBSTR(documentno, '/([0-9]+)$'), 2)) docno from c_order where documentno like (select CONCAT(orderdocno_prefix , '/%') from obpos_applications where value = '"
+          + searchKey + "') and c_doctype_id = '" + documentTypeId + "' ) a";
+    } else {
+      // unknow DBMS
+      // shouldn't happen
+      log.error("Error getting max documentNo because the DBMS is unknow.");
+      return 0;
+    }
 
-    ScrollableResults POSOrders = obqOrders.scroll(ScrollMode.FORWARD_ONLY);
-    int maxNumber = 0;
-    int i = 0;
-    while (POSOrders.next()) {
-      Order order = (Order) POSOrders.get(0);
-      String documentNo = order.getDocumentNo();
-      // documentNo = prefix + '/' + number
-      String onlyNumber = documentNo.split("/")[1];
+    int number = 0;
+    ConnectionProviderImpl con = null;
+    Connection connection = null;
+    try {
+      con = new ConnectionProviderImpl(OBPropertiesProvider.getInstance().getOpenbravoProperties());
+      connection = con.getConnection();
+      PreparedStatement ps = connection.prepareStatement(sqlToExecute);
+      ResultSet rs = ps.executeQuery();
+      while (rs.next()) {
+        number = rs.getInt(1);
+      }
+      rs.close();
+      ps.close();
+    } catch (Exception e) {
+      log.error("An error happened while getting max documentNo. Max document number is 0", e);
+      number = 0;
+      // TODO: handle exception
+    } finally {
       try {
-        int number = Integer.parseInt(onlyNumber);
-        if (number > maxNumber) {
-          maxNumber = number;
+        if (connection != null) {
+          connection.close();
         }
-      } catch (NumberFormatException e) {
-        // If the parsed result is not a number (i.e. because the searchKey is a
-        // prefix of another POS searchKey, the result is ignored
+      } catch (Exception e) {
+        // do nothing
       }
-      i++;
-      if (i % 100 == 0) {
-        OBDal.getInstance().getSession().clear();
+      try {
+        if (con != null) {
+          con.destroy();
+        }
+      } catch (Exception e) {
+        // do nothing
       }
     }
-    return maxNumber;
+    return number;
   }
 
   public static String getRetailDependantModuleIds() {