Improved the cache key for the groupBy operation

- correctly reflects the calculated aggregates and
- uses column indices instead of variable names

src/engine/GroupBy.cpp

@@ -46,16 +46,24 @@ void GroupBy::setSubtree(std::shared_ptr<QueryExecutionTree> subtree) {
 }
 
 string GroupBy::asString(size_t indent) const {
+  const auto varMap = getVariableColumns();
+  const auto varMapInput = _subtree->getVariableColumns();
   std::ostringstream os;
   for (size_t i = 0; i < indent; ++i) {
     os << " ";
   }
   os << "GROUP_BY ";
   for (const std::string var : _groupByVariables) {
-    os << var << ", ";
+    os << varMap.at(var) << ", ";
   }
   for (auto p : _aliases) {
-    os << p._function << ", ";
+
+    os << ParsedQuery::AggregateTypeAsString(p._type);
+    if (p._type == ParsedQuery::AggregateType::GROUP_CONCAT) {
+      os << p._delimiter;
+    }
+
+    os << ' ' << varMapInput.at(p._inVarName) << ' ' << varMap.at(p._outVarName);
   }
   os << std::endl;
   os << _subtree->asString(indent);

src/parser/ParsedQuery.h

@@ -11,6 +11,7 @@
 #include "../util/HashMap.h"
 #include "../util/StringUtils.h"
 #include "ParseException.h"
+#include "../util/Exception.h"
 
 using std::string;
 using std::vector;
@@ -264,6 +265,31 @@ class ParsedQuery {
     AVG
   };
 
+  static std::string AggregateTypeAsString(AggregateType t) {
+    switch(t) {
+      case  AggregateType::COUNT:
+        return "COUNT";
+      case AggregateType::GROUP_CONCAT:
+        return "GROUP_CONCAT";
+      case AggregateType::FIRST:
+        return "FIRST";
+      case AggregateType::LAST:
+        return "LAST";
+      case AggregateType::SAMPLE:
+        return "SAMPLE";
+      case AggregateType::MIN:
+        return "MIN";
+      case AggregateType::MAX:
+        return "MAX";
+      case AggregateType::SUM:
+        return "SUM";
+      case AggregateType::AVG:
+        return "AVG";
+      default:
+        AD_THROW(ad_semsearch::Exception::CHECK_FAILED, "Illegal/unimplemented enum value in AggregateTyppeAsString. Should never happen, please report this");
+    }
+  }
+
   struct Alias {
     AggregateType _type;
     string _inVarName;