Auto-project on distinct inequality fields.

service/datastore/finalized_query.go

Index: service/datastore/finalized_query.go
diff --git a/service/datastore/finalized_query.go b/service/datastore/finalized_query.go
index 8a6d75725dc054ef419ee23b5c0f38bd01bcf762..393d06654838df95f7ff7247b284582906b7d96c 100644
--- a/service/datastore/finalized_query.go
+++ b/service/datastore/finalized_query.go
@@ -65,11 +65,23 @@ func (q *FinalizedQuery) EventuallyConsistent() bool {
 // Project is the list of fields that this query projects on, or empty if this
 // is not a projection query.
 func (q *FinalizedQuery) Project() []string {
-	if len(q.project) == 0 {
+	// For distinct queries with an inequality filter, one must first project the
+	// inequality field.
+	size := len(q.project)
+	ineqDistinctProject := ""
+	if q.distinct && q.ineqFiltProp != "" {
+		ineqDistinctProject = q.ineqFiltProp
+		size++
+	}
+
+	if size == 0 {
 		return nil
 	}
-	ret := make([]string, len(q.project))
-	copy(ret, q.project)
+	ret := make([]string, 0, size)
+	if ineqDistinctProject != "" {
+		ret = append(ret, ineqDistinctProject)
+	}
+	ret = append(ret, q.project...)

[iannucci, 2016/02/27 00:58:51]

ditch this whole thing

 	return ret
 }