From e266efdf966252afce690eb490b162ce314e55e2 Mon Sep 17 00:00:00 2001
From: Jan <jsteemann@users.noreply.github.com>
Date: Wed, 25 Jul 2018 17:33:45 +0200
Subject: [PATCH] fixed issue #5977: Unexpected execution plan when subquery
 contains COLLECT (#5983)

---
 CHANGELOG                           |  2 ++
 arangod/Aql/CollectBlock.cpp        |  3 +++
 js/server/tests/aql/aql-distinct.js | 11 +++++++++++
 3 files changed, 16 insertions(+)

diff --git a/CHANGELOG b/CHANGELOG
index 44ee4a5818..b9191f714a 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,6 +1,8 @@
 v3.3.13 (XXXX-XX-XX)
 --------------------
 
+* fixed issue #5977: Unexpected execution plan when subquery contains COLLECT
+
 * Bugfix: The AQL syntax variants `UPDATE/REPLACE k WITH d` now correctly take
   _rev from k instead of d (when ignoreRevs is false) and ignore d._rev.
 
diff --git a/arangod/Aql/CollectBlock.cpp b/arangod/Aql/CollectBlock.cpp
index 7a1e794d0d..22e744dfa0 100644
--- a/arangod/Aql/CollectBlock.cpp
+++ b/arangod/Aql/CollectBlock.cpp
@@ -973,6 +973,9 @@ int DistinctCollectBlock::getOrSkipSome(size_t atLeast, size_t atMost,
       if (!skipping) {
         size_t i = 0;
         for (auto& it : _groupRegisters) {
+          if (skipped > 0) {
+            res->copyValuesFromFirstRow(skipped, static_cast<RegisterId>(cur->getNrRegs()));
+          }
           res->setValue(skipped, it.first, groupValues[i].clone());
           ++i;
         }
diff --git a/js/server/tests/aql/aql-distinct.js b/js/server/tests/aql/aql-distinct.js
index ac84e7a4de..d23f75f9c9 100644
--- a/js/server/tests/aql/aql-distinct.js
+++ b/js/server/tests/aql/aql-distinct.js
@@ -207,6 +207,17 @@ function ahuacatlDistinct () {
       assertEqual(100, integers.length);
       assertEqual(100, strings.length);
     },
+            
+    testDistinctInOptimizedAwaySubquery : function () {
+      let query = "LET values = (FOR i IN " + c.name() + " RETURN DISTINCT i.value1) FOR doc IN values RETURN 42";
+      containsDistinct(query);
+      let result = AQL_EXECUTE(query).json;
+
+      assertEqual(100, result.length);
+  
+      let plan = AQL_EXPLAIN(query).plan;
+      assertNotEqual(-1, plan.rules.indexOf("inline-subqueries"));
+    },
 
 ////////////////////////////////////////////////////////////////////////////////
 /// @brief distinct usage