Simplification of the select. The query for select used fields which are not...

Simplification of the select. The query for select used fields which are not part of the unique key. We also get the API to issue a throw the moment we miss the xref id retrieval. This should be an impossible scenario to get into though

modules/Bio/EnsEMBL/DBSQL/DBEntryAdaptor.pm

@@ -885,28 +885,26 @@ sub _store_or_fetch_xref {
         
     } else { # xref_id already exists, retrieve it
         my $sql = 'SELECT xref_id FROM xref 
-            WHERE 
-                dbprimary_acc = ?
-            AND display_label = ?
+            WHERE dbprimary_acc = ?
             AND version = ?
             AND external_db_id = ?
             AND info_type = ?
-            AND info_text = ?
-            AND description';
-        if (defined $dbEntry->description) {$sql .= ' = ?'}
-        else {$sql .= ' is NULL'}
+            AND info_text = ?';
 
         $sth = $self->prepare( $sql );
         $sth->bind_param(1, $dbEntry->primary_id,SQL_VARCHAR);
-        $sth->bind_param(2, ($dbEntry->display_id || ''),SQL_VARCHAR);
-        $sth->bind_param(3, $dbEntry->version ,SQL_VARCHAR);
-        $sth->bind_param(4, $dbRef,SQL_INTEGER);
-        $sth->bind_param(5, ($dbEntry->info_type || 'NONE'), SQL_VARCHAR);
-        $sth->bind_param(6, ($dbEntry->info_text || ''), SQL_VARCHAR);
-        if (defined $dbEntry->description) {$sth->bind_param(7, $dbEntry->description,SQL_VARCHAR);}
+        $sth->bind_param(2, $dbEntry->version ,SQL_VARCHAR);
+        $sth->bind_param(3, $dbRef, SQL_INTEGER);
+        $sth->bind_param(4, ($dbEntry->info_type || 'NONE'), SQL_VARCHAR);
+        $sth->bind_param(5, ($dbEntry->info_text || ''), SQL_VARCHAR);
         $sth->execute();
         ($xref_id) = $sth->fetchrow_array();
         $sth->finish;
+        
+        if(!$xref_id) {
+          my $msg = 'Cannot find an xref id for %s (%d) with external db id %d';
+          throw(sprintf($msg, $dbEntry->primary_id(), $dbEntry->version(), $dbRef))
+        }
     }
     
     return $xref_id;