Optimize First calls by using Limit 1

First operator gets handled by Single call in MartenQueryExecutor as result should be one be then
JasperFx · Nov 23, 2015 · 1f0c737 · 1f0c737
1 parent b9e82a3
commit 1f0c737
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Showing 2 changed files with 13 additions and 7 deletions.
diff --git a/src/Marten/Linq/DocumentQuery.cs b/src/Marten/Linq/DocumentQuery.cs
@@ -92,7 +92,18 @@ private string appendLimit(string sql)
             var take =
                 _query.ResultOperators.OfType<TakeResultOperator>().OrderByDescending(x => x.Count).FirstOrDefault();
 
-            return take == null ? sql : sql + " LIMIT " + take.Count + " ";
+            var first = _query.ResultOperators.OfType<FirstResultOperator>().FirstOrDefault();
+
+            string limitNumber = null;
+            if (take != null)
+            {
+                limitNumber = take.Count.ToString();
+            }
+            else if (first != null)
+            {
+                limitNumber = "1";
+            }
+            return limitNumber == null ? sql : sql + " LIMIT " + limitNumber + " ";
         }
 
         private string toOrderClause()

diff --git a/src/Marten/Linq/MartenQueryExecutor.cs b/src/Marten/Linq/MartenQueryExecutor.cs
@@ -63,7 +63,6 @@ T IQueryExecutor.ExecuteScalar<T>(QueryModel queryModel)
 
         T IQueryExecutor.ExecuteSingle<T>(QueryModel queryModel, bool returnDefaultWhenEmpty)
         {
-            var isFirst = queryModel.ResultOperators.OfType<FirstResultOperator>().Any();
             var isLast = queryModel.ResultOperators.OfType<LastResultOperator>().Any();
 
             // TODO -- optimize by using Top 1
@@ -73,11 +72,7 @@ T IQueryExecutor.ExecuteSingle<T>(QueryModel queryModel, bool returnDefaultWhenE
             if (returnDefaultWhenEmpty && all.Length == 0) return default(T);
 
             string data = null;
-            if (isFirst)
-            {
-                data = all.First();
-            }
-            else if (isLast)
+            if (isLast)
             {
                 data = all.Last();
             }