fixed issue arangodb#6031: Broken LIMIT in nested list iterations (arangodb#6032)

jsteemann · web-flow · commit 0660044448ee · 2018-08-01T08:29:57.000+02:00
diff --git a/CHANGELOG b/CHANGELOG
@@ -1,3 +1,9 @@
+v3.3.14 (XXXX-XX-XX)
+--------------------
+
+* fixed issue #6031: Broken LIMIT in nested list iterations 
+
+
 v3.3.13 (2018-07-26)
 --------------------
 
diff --git a/arangod/Aql/EnumerateListBlock.cpp b/arangod/Aql/EnumerateListBlock.cpp
@@ -111,12 +111,13 @@ AqlItemBlock* EnumerateListBlock::getSome(size_t, size_t atMost) {
     else {
       sizeInVar = inVarReg.length();
     }
+        
 
     if (sizeInVar == 0) {
       res = nullptr;
     } else {
       size_t toSend = (std::min)(atMost, sizeInVar - _index);
-
+        
       // create the result
       res.reset(requestBlock(toSend, getPlanNode()->getRegisterPlan()->nrRegs[getPlanNode()->getDepth()]));
 
@@ -146,6 +147,7 @@ AqlItemBlock* EnumerateListBlock::getSome(size_t, size_t atMost) {
 
     if (_index == sizeInVar) {
       _index = 0;
+        
       // advance read position in the current block . . .
       if (++_pos == cur->size()) {
         returnBlock(cur);
@@ -169,7 +171,7 @@ size_t EnumerateListBlock::skipSome(size_t atLeast, size_t atMost) {
   }
 
   size_t skipped = 0;
-
+        
   while (skipped < atLeast) {
     if (_buffer.empty()) {
       size_t toFetch = (std::min)(DefaultBatchSize(), atMost);
@@ -202,13 +204,15 @@ size_t EnumerateListBlock::skipSome(size_t atLeast, size_t atMost) {
     else {
       sizeInVar = inVarReg.length();
     }
-
+        
     if (atMost < sizeInVar - _index) {
       // eat just enough of inVariable . . .
+      atLeast -= atMost;
       _index += atMost;
       skipped += atMost;
     } else {
       // eat the whole of the current inVariable and proceed . . .
+      atLeast -= (sizeInVar - _index);
       skipped += (sizeInVar - _index);
       _index = 0;
       if (++_pos == cur->size()) {
diff --git a/js/server/tests/aql/aql-queries-optimizer-limit-noncluster.js b/js/server/tests/aql/aql-queries-optimizer-limit-noncluster.js
@@ -777,6 +777,15 @@ function ahuacatlQueryOptimizerLimitTestSuite () {
         var actual = getQueryResults(query[0]);
         assertEqual(query[1], actual, query);
       });
+    },
+
+    testLimitNestedLoops: function() {
+      let expected = [[1, 1], [1, 2], [1, 3], [1, 4], [2, 1], [2, 2], [2, 3], [2, 4]];
+      let query = "FOR i IN 1..2 FOR j IN 1..4 LIMIT @limit, 2 RETURN [i , j]";
+      for (let i = 0; i <= 8; ++i) {
+        let actual = getQueryResults(query, { limit: i });
+        assertEqual(expected.slice(i, i + 2), actual, i);
+      }
     }
 
   };
