disabled exception during overriding settings with same value in readonly mode [#CLICKHOUSE-3041]

dbms/src/DataStreams/FormatFactory.cpp

@@ -121,7 +121,7 @@ static BlockOutputStreamPtr getOutputImpl(const String & name, WriteBuffer & buf
     const Block & sample, const Context & context)
 {
     const Settings & settings = context.getSettingsRef();
-    FormatSettingsJSON json_settings(settings.output_format_json_quote_64bit_integers, true);
+    FormatSettingsJSON json_settings(settings.output_format_json_quote_64bit_integers, settings.output_format_json_quote_denormals);
 
     if (name == "Native")
         return std::make_shared<NativeBlockOutputStream>(buf);

dbms/src/DataTypes/DataTypeNumberBase.cpp

@@ -65,7 +65,6 @@ void DataTypeNumberBase<T>::deserializeTextQuoted(IColumn & column, ReadBuffer &
 template <typename T>
 void DataTypeNumberBase<T>::serializeTextJSON(const IColumn & column, size_t row_num, WriteBuffer & ostr, const FormatSettingsJSON & settings) const
 {
-    writeCString(settings.output_format_json_quote_denormals ? "1" : "0", ostr);
     auto x = static_cast<const ColumnVector<T> &>(column).getData()[row_num];
     bool is_finite = isFinite(x);
 

dbms/src/Interpreters/Limits.h

@@ -171,6 +171,19 @@ struct Limits
     #undef TRY_SET
     }
 
+    bool tryGet(const String & name, String & value) const
+    {
+    #define TRY_GET(TYPE, NAME, DEFAULT) \
+        else if (name == #NAME) { value = NAME.toString(); return true; }
+
+        if (false) {}
+        APPLY_FOR_LIMITS(TRY_GET)
+
+        return false;
+
+    #undef TRY_GET
+    }
+
 private:
     friend struct Settings;
 

dbms/src/Interpreters/Settings.cpp

@@ -69,6 +69,37 @@ void Settings::set(const String & name, const String & value)
 #undef TRY_SET
 }
 
+String Settings::get(const String & name) const
+{
+#define GET(TYPE, NAME, DEFAULT) \
+    else if (name == #NAME) return NAME.toString();
+
+    if (false) {}
+    APPLY_FOR_SETTINGS(GET)
+    else
+    {
+        String value;
+        if (!limits.tryGet(name, value))
+            throw Exception("Unknown setting " + name, ErrorCodes::UNKNOWN_SETTING);
+        return value;
+    }
+
+#undef GET
+}
+
+bool Settings::tryGet(const String & name, String & value) const
+{
+#define TRY_GET(TYPE, NAME, DEFAULT) \
+    else if (name == #NAME) { value = NAME.toString(); return true; }
+
+    if (false) {}
+    APPLY_FOR_SETTINGS(TRY_GET)
+    else
+        return limits.tryGet(name, value);
+
+#undef TRY_GET
+}
+
 /** Set the settings from the profile (in the server configuration, many settings can be listed in one profile).
     * The profile can also be set using the `set` functions, like the `profile` setting.
     */

dbms/src/Interpreters/Settings.h

@@ -233,6 +233,9 @@ struct Settings
     /** Controls quoting of 64-bit integers in JSON output format. */ \
     M(SettingBool, output_format_json_quote_64bit_integers, true) \
     \
+    /** Enables "+nan", "-nan", "+inf", "-inf" outputs in JSON output format. */ \
+    M(SettingBool, output_format_json_quote_denormals, false) \
+    \
     /** Rows limit for Pretty formats. */ \
     M(SettingUInt64, output_format_pretty_max_rows, 10000) \
     \
@@ -302,6 +305,11 @@ struct Settings
     /// Set setting by name. Read value in text form from string (for example, from configuration file or from URL parameter).
     void set(const String & name, const String & value);
 
+    /// Get setting by name. Converts value to String.
+    String get(const String & name) const;
+
+    bool tryGet(const String & name, String & value) const;
+
     /** Set multiple settings from "profile" (in server configuration file (users.xml), profiles contain groups of multiple settings).
       * The profile can also be set using the `set` functions, like the profile setting.
       */

dbms/src/Server/HTTPHandler.cpp

@@ -429,6 +429,8 @@ void HTTPHandler::processQuery(
         "session_id", "session_timeout", "session_check"
     };
 
+    const Settings & settings = context.getSettingsRef();
+
     for (auto it = params.begin(); it != params.end(); ++it)
     {
         if (it->first == "database")
@@ -445,7 +447,9 @@ void HTTPHandler::processQuery(
         else
         {
             /// All other query parameters are treated as settings.
-
+            String value;
+            if (!settings.tryGet(it->first, value) || it->second != value)
+            {
                 if (readonly_before_query == 1)
                     throw Exception("Cannot override setting (" + it->first + ") in readonly mode", ErrorCodes::READONLY);
 
@@ -455,8 +459,7 @@ void HTTPHandler::processQuery(
                 context.setSetting(it->first, it->second);
             }
         }
-
-    const Settings & settings = context.getSettingsRef();
+    }
 
     /// HTTP response compression is turned on only if the client signalled that they support it
     /// (using Accept-Encoding header) and 'enable_http_compression' setting is turned on.