Better info in log #2246

dbms/src/Interpreters/InterpreterFactory.cpp

@@ -50,7 +50,14 @@ namespace ErrorCodes
 static void throwIfReadOnly(Context & context)
 {
     if (context.getSettingsRef().readonly)
-        throw Exception("Cannot execute query in readonly mode", ErrorCodes::READONLY);
+    {
+        const auto & client_info = context.getClientInfo();
+        if (client_info.interface == ClientInfo::Interface::HTTP && client_info.http_method == ClientInfo::HTTPMethod::GET)
+            throw Exception("Cannot execute query in readonly mode. "
+                "For queries over HTTP, method GET implies readonly. You should use method POST for modifying queries.", ErrorCodes::READONLY);
+        else
+            throw Exception("Cannot execute query in readonly mode", ErrorCodes::READONLY);
+    }
 }
 
 

dbms/src/Interpreters/Set.h

@@ -176,7 +176,10 @@ public:
 
     MergeTreeSetIndex(const SetElements & set_elements, std::vector<KeyTuplePositionMapping> && indexes_mapping_);
 
+    size_t size() const { return ordered_set.size(); }
+
     BoolMask mayBeTrueInRange(const std::vector<Range> & key_ranges, const DataTypes & data_types);
+
 private:
     using OrderedTuples = std::vector<std::vector<FieldWithInfinity>>;
     OrderedTuples ordered_set;

dbms/src/Storages/MergeTree/KeyCondition.cpp

@@ -1105,7 +1105,8 @@ String KeyCondition::RPNElement::toString() const
         {
             ss << "(";
             print_wrapped_column(ss);
-            ss << (function == FUNCTION_IN_SET ? " in set" : " notIn set");
+            ss << (function == FUNCTION_IN_SET ? " in " : " notIn ");
+            ss << set_index->size() << "-element set";
             ss << ")";
             return ss.str();
         }