Optimize load_id(), load() sequence for SQLite and PostgreSQL

In these databases both of these functions load the data into the
object image. If there is no chance of image overwrite between
these calls, then we don't need to load the image the second time.

1 files changed, 7 insertions, 1 deletions

diff --git a/odb/object-result.hxx b/odb/object-result.hxx
index e4d28ee..8b0b502 100644
--- a/odb/object-result.hxx
+++ b/odb/object-result.hxx
@@ -111,8 +111,14 @@ namespace odb
     }
 
   protected:
+    // The fetch argument is a hint to the implementation. If it is
+    // false then it means load_id() was already called (and presumably
+    // fetched the data into the object image) and the object image
+    // is still valid (so the implementation doesn't need to fetch
+    // the data again).
+    //
     virtual void
-    load (object_type&) = 0;
+    load (object_type&, bool fetch = true) = 0;
 
     virtual id_type
     load_id () = 0;