perf example

performance/srv/performance-service.cds

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+using { sap.capire.performance as my } from '../db/schema';
+
+service PerformanceService {
+  entity OrdersHeaders as projection on my.OrdersHeaders;
+  entity OrdersItems   as projection on my.OrdersItems;
+  entity Books      as projection on my.Books;
+  entity Authors      as projection on my.Authors;
+
+// static
+view OrdersItemsViewJoin as select 
+
+    OrdersHeaders.ID        as Header_ID, 
+    OrdersHeaders.OrderNo   as OrderNo, 
+    OrdersHeaders.buyer     as buyer, 
+    OrdersHeaders.currency  as currency,
+    key OrdersItems.ID      as Item_ID,
+    OrdersItems.product     as product,
+    OrdersItems.quantity    as quantity,
+    OrdersItems.title       as title,
+    OrdersItems.price       as price
+
+ from OrdersHeaders JOIN OrdersItems on OrdersHeaders.ID = OrdersItems.Header.ID;
+
+// dynamic entity
+entity OrderItemsViewAssoc as projection on OrdersHeaders;
+
+// sort on right table
+view SortedOrdersJoin as select 
+    OrdersHeaders.ID        as Header_ID, 
+    OrdersHeaders.OrderNo   as OrderNo, 
+    OrdersHeaders.buyer     as buyer, 
+    OrdersHeaders.currency  as currency,
+    key OrdersItems.ID      as Item_ID,
+    OrdersItems.product     as product,
+    OrdersItems.quantity    as quantity,
+    OrdersItems.title       as title,
+    OrdersItems.price       as price
+from OrdersHeaders JOIN OrdersItems on OrdersHeaders.ID = OrdersItems.Header.ID
+order by title;
+
+// sort on items and join back to header via assoc
+
+view SortedOrdersAssoc as select
+from OrdersItems {*, Header.OrderNo, Header.buyer, Header.currency }
+order by OrdersItems.title;
+
+// filter on right table 
+
+view FilteredOrdersJoin as select 
+    OrdersHeaders.ID        as Header_ID, 
+    OrdersHeaders.OrderNo   as OrderNo, 
+    OrdersHeaders.buyer     as buyer, 
+    OrdersHeaders.currency  as currency,
+    key OrdersItems.ID          as Item_ID,
+    OrdersItems.product     as product,
+    OrdersItems.quantity    as quantity,
+    OrdersItems.title       as title,
+    OrdersItems.price       as price
+from OrdersHeaders JOIN OrdersItems on OrdersHeaders.ID = OrdersItems.Header.ID
+where price > 100;
+
+// filter on items and join back to header via assoc
+
+view FilteredOrdersAssoc as select
+from OrdersItems {*, Header.OrderNo, Header.buyer, Header.currency }
+where OrdersItems.price > 100;
+
+
+// TODO avoid CASE and/or JOIN: Denormalization of expensive complex structures, 
+// calculate on write instead of read
+
+// CASE -> try to remodel to avoid CASE, if re-modelling is not possible, 
+// fill redundant fields at write
+
+entity OrdersItemsCaseView as projection on OrdersItems {
+    *,
+    case  
+       when quantity > 500 then 'Large'
+       when quantity > 100 then 'Medium'       
+       else 'Small'
+    end as category : String
+};
+
+
+
+}
+