diff --git a/storage/tracking.lisp b/storage/tracking.lisp
index 8cba05e..9877b2c 100644
--- a/storage/tracking.lisp
+++ b/storage/tracking.lisp
@@ -45,6 +45,75 @@
 (defun make-item (cont &rest head)
   (make-instance (item-class cont) :head head :container cont))
 
+(defun query-last (cont &rest head-specs)
+  (query1 cont (make-where head-specs)))
+   
+(defun get-track (cont trid) 
+  (query1 cont (make-where (list (list :trackid trid)))))
+  ;(query1 cont (list := :trackid trid)))
+
+(defun query1 (cont crit)
+  (let* ((tr (make-item cont))
+         (st (storage cont))
+         (table (storage:qualified-table-name st (table-name cont)))
+         (cols (cons :trackid (append (shape:head-fields tr) '(:timestamp :data))))
+         (row (storage:normalize-plist (car (storage:query st
+           (sxql:select cols
+             (sxql:from table) 
+             (sxql:where crit)
+             (sxql:order-by (:desc :timestamp))
+             (sxql:limit 1)))))))
+    (setup-track tr row)))
+
+(defun insert (track)
+  (ensure-timestamp track)
+  (let* ((cont (container track))
+         (st (storage cont))
+         (table (storage:qualified-table-name st (table-name cont)))
+         (res (car (storage:query st
+           (sxql:insert-into table
+             (apply #'sxql:make-clause ':set= (plist track))
+             (sxql:returning :trackid))))))
+    (setf (trackid track) (cadr res))
+    track))
+
+(defun update (track)
+  (ensure-timestamp track)
+  (let* ((cont (container track))
+         (st (storage cont))
+         (table (storage:qualified-table-name st (table-name cont))))
+    (sxql:update table
+      (apply #'sxql:make-clause ':set= (plist track))
+      (where (:= :trackid (trackid track))))))
+
+;;;; auxiliary functions for queries, ...
+
+(defun make-where (specs)
+  (let (crit)
+    (dolist (spec specs)
+      (destructuring-bind (f v &optional op) spec
+        (when v
+          (when (eq f :time-stamp)
+            (setf f :timestamp))
+          (unless op
+            (setf op (if (eq f :timestamp) :>= :=)))
+          (push (list op f v) crit))))
+    (if (cdr crit)
+      (cons :and crit)
+      (car crit))))
+
+(defun setup-track (tr row)
+  ;(log:info "tr: ~s, row: ~s" tr row)
+  (let ((hv (mapcar #'(lambda (x) (util:to-keyword (getf row x)))
+                    (shape:head-fields tr))))
+    (setf (shape:head tr) hv)
+    (setf (trackid tr) (getf row :trackid))
+    (setf (time-stamp tr) (getf row :timestamp))
+    (setf (shape:data tr) 
+          (funcall *build-track-data*
+            (jzon:parse (getf row :data) :key-fn #'util:to-keyword)))
+    tr))
+
 (defun ensure-timestamp (track)
   (if (not (time-stamp track))
     (setf (time-stamp track) (get-universal-time))))
@@ -59,41 +128,8 @@
           (setf data (alx:plist-hash-table data)))
         (setf (getf vl :data) (jzon:stringify data))))
     vl))
-   
-(defun insert (track)
-  (ensure-timestamp track)
-  (let* ((cont (container track))
-         (st (storage cont))
-         (table (storage:qualified-table-name st (table-name cont)))
-         (res (car (storage:query st
-           (sxql:insert-into table
-             (apply #'sxql:make-clause ':set= (plist track))
-             (sxql:returning :trackid))))))
-    (setf (trackid track) (cadr res))
-    track))
 
-(defun get-track (cont trid) 
-  (let* ((tr (make-item cont))
-         (st (storage cont))
-         (table (storage:qualified-table-name st (table-name cont)))
-         (cols (append (shape:head-fields tr) '(:timestamp :data)))
-         (row (storage:normalize-plist (car (storage:query st
-           (sxql:select cols
-             (sxql:from table) 
-             (sxql:where (:= :trackid trid))))))))
-    (setup-track tr row)))
-
-(defun setup-track (tr row)
-  ;(log:info "tr: ~s, row: ~s" tr row)
-  (let ((hv (mapcar #'(lambda (x) (util:to-keyword (getf row x)))
-                    (shape:head-fields tr))))
-    (setf (shape:head tr) hv)
-    (setf (trackid tr) (getf row :trackid))
-    (setf (time-stamp tr) (getf row :timestamp))
-    (setf (shape:data tr) 
-          (funcall *build-track-data*
-            (jzon:parse (getf row :data) :key-fn #'util:to-keyword)))
-    tr))
+;;;; create table and indexes
 
  (defun create-table (cont) 
   (let* ((st (storage cont))