3 files changed, 47 insertions, 8 deletions

diff --git a/src/backenddb/pg_lookup_products.c b/src/backenddb/pg_lookup_products.c
index d16aeb8d..fa2887a8 100644
--- a/src/backenddb/pg_lookup_products.c
+++ b/src/backenddb/pg_lookup_products.c
@@ -65,9 +65,12 @@ lookup_products_cb (void *cls,
   for (unsigned int i = 0; i < num_results; i++)
   {
     char *product_id;
+    uint64_t product_serial;
     struct GNUNET_PQ_ResultSpec rs[] = {
       GNUNET_PQ_result_spec_string ("product_id",
                                     &product_id),
+      GNUNET_PQ_result_spec_uint64 ("product_serial",
+                                    &product_serial),
       GNUNET_PQ_result_spec_end
     };
 
@@ -81,6 +84,7 @@ lookup_products_cb (void *cls,
       return;
     }
     plc->cb (plc->cb_cls,
+             product_serial,
              product_id);
     GNUNET_PQ_cleanup_result (rs);
   }
@@ -90,10 +94,13 @@ lookup_products_cb (void *cls,
 enum GNUNET_DB_QueryStatus
 TMH_PG_lookup_products (void *cls,
                         const char *instance_id,
+                        uint64_t offset,
+                        int64_t limit,
                         TALER_MERCHANTDB_ProductsCallback cb,
                         void *cb_cls)
 {
   struct PostgresClosure *pg = cls;
+  uint64_t plimit = (uint64_t) ((limit < 0) ? -limit : limit);
   struct LookupProductsContext plc = {
     .cb = cb,
     .cb_cls = cb_cls,
@@ -102,24 +109,45 @@ TMH_PG_lookup_products (void *cls,
   };
   struct GNUNET_PQ_QueryParam params[] = {
     GNUNET_PQ_query_param_string (instance_id),
+    GNUNET_PQ_query_param_uint64 (&offset),
+    GNUNET_PQ_query_param_uint64 (&plimit),
     GNUNET_PQ_query_param_end
   };
   enum GNUNET_DB_QueryStatus qs;
 
   check_connection (pg);
   PREPARE (pg,
-           "lookup_products",
+           "lookup_products_asc",
            "SELECT"
-           " product_id"
+           "  product_id"
+           " ,product_serial"
            " FROM merchant_inventory"
            " JOIN merchant_instances"
            "   USING (merchant_serial)"
-           " WHERE merchant_instances.merchant_id=$1");
-  qs = GNUNET_PQ_eval_prepared_multi_select (pg->conn,
-                                             "lookup_products",
-                                             params,
-                                             &lookup_products_cb,
-                                             &plc);
+           " WHERE merchant_instances.merchant_id=$1"
+           "   AND product_serial > $2"
+           " ORDER BY product_serial ASC"
+           " LIMIT $3");
+  PREPARE (pg,
+           "lookup_products_desc",
+           "SELECT"
+           "  product_id"
+           " ,product_serial"
+           " FROM merchant_inventory"
+           " JOIN merchant_instances"
+           "   USING (merchant_serial)"
+           " WHERE merchant_instances.merchant_id=$1"
+           "   AND product_serial < $2"
+           " ORDER BY product_serial DESC"
+           " LIMIT $3");
+  qs = GNUNET_PQ_eval_prepared_multi_select (
+    pg->conn,
+    (limit > 0)
+    ? "lookup_products_asc"
+    : "lookup_products_desc",
+    params,
+    &lookup_products_cb,
+    &plc);
   /* If there was an error inside lookup_products_cb, return a hard error. */
   if (plc.extract_failed)
     return GNUNET_DB_STATUS_HARD_ERROR;
diff --git a/src/backenddb/pg_lookup_products.h b/src/backenddb/pg_lookup_products.h
index 398b5eac..d96328c8 100644
--- a/src/backenddb/pg_lookup_products.h
+++ b/src/backenddb/pg_lookup_products.h
@@ -30,6 +30,9 @@
  *
  * @param cls closure
  * @param instance_id instance to lookup products for
+ * @param offset transfer_serial number of the transfer we want to offset from
+ * @param limit number of entries to return, negative for descending,
+ *                positive for ascending
  * @param cb function to call on all products found
  * @param cb_cls closure for @a cb
  * @return database result code
@@ -37,6 +40,8 @@
 enum GNUNET_DB_QueryStatus
 TMH_PG_lookup_products (void *cls,
                         const char *instance_id,
+                        uint64_t offset,
+                        int64_t limit,
                         TALER_MERCHANTDB_ProductsCallback cb,
                         void *cb_cls);
 
diff --git a/src/backenddb/test_merchantdb.c b/src/backenddb/test_merchantdb.c
index 53902b3d..60a0b08b 100644
--- a/src/backenddb/test_merchantdb.c
+++ b/src/backenddb/test_merchantdb.c
@@ -906,13 +906,17 @@ struct TestLookupProducts_Closure
  * Function called after calling @e test_lookup_products
  *
  * @param cls a pointer to the lookup closure.
+ * @param product_serial DB row ID
  * @param product_id the identifier of the product found.
  */
 static void
 lookup_products_cb (void *cls,
+                    uint64_t product_serial,
                     const char *product_id)
 {
   struct TestLookupProducts_Closure *cmp = cls;
+
+  GNUNET_assert (product_serial > 0);
   if (NULL == cmp)
     return;
   cmp->results_length += 1;
@@ -948,6 +952,8 @@ test_lookup_products (const struct InstanceData *instance,
   memset (results_matching, 0, sizeof (unsigned int) * products_length);
   if (0 > plugin->lookup_products (plugin->cls,
                                    instance->instance.id,
+                                   0,
+                                   20,
                                    &lookup_products_cb,
                                    &cls))
   {