From ae5324716b50484f269a74e11c0afddd6232b45e Mon Sep 17 00:00:00 2001
From: Tessa Conway <tessa.conway@cde.catapult.org.uk>
Date: Mon, 5 Sep 2016 17:33:37 +0100
Subject: [PATCH] Fix generic query so limiting of data happens upfront and not
 at the end - performance improvement

---
 repository/models/queries/generic.py | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/repository/models/queries/generic.py b/repository/models/queries/generic.py
index a52aa8d..d972a4c 100644
--- a/repository/models/queries/generic.py
+++ b/repository/models/queries/generic.py
@@ -84,20 +84,24 @@
         SELECT ?{id_name} (MAX(?when) AS ?last_modified)
 
         WHERE {{
-            ?{id_name} a {class} .
-            OPTIONAL {{ ?{id_name} dcterm:modified ?when  }}
-
-            {filter}
+            {{ SELECT ?{id_name} {{
+                ?{id_name} a {class} .
+                OPTIONAL {{ ?{id_name} dcterm:modified ?when  }}
+
+                {filter}
+          }} LIMIT {page_size}
+             OFFSET {offset}
+         }}
+         OPTIONAL {{ ?{id_name} dcterm:modified ?when }}
         }}
         GROUP BY ?{id_name}
     }}
     {extra_query}
 }}
 ORDER BY ?last_modified
-LIMIT {page_size}
-OFFSET {offset}
 """
 
+
 INSERT_DATA = """
 INSERT DATA {
 %s