Merge pull request ClickHouse#68977 from ClickHouse/backport/24.8/68793

Backport ClickHouse#68793 to 24.8: Check setting use_json_alias_for_old_object_type in runtime

Author: robot-ch-test-poll4

docs/en/operations/settings/settings.md

@@ -5623,7 +5623,6 @@ Default value: `1GiB`.
 ## use_json_alias_for_old_object_type
 
 When enabled, `JSON` data type alias will be used to create an old [Object('json')](../../sql-reference/data-types/json.md) type instead of the new [JSON](../../sql-reference/data-types/newjson.md) type.
-This setting requires server restart to take effect when changed.
 
 Default value: `false`.
 

src/DataTypes/DataTypeObject.cpp

@@ -1,10 +1,12 @@
 #include <DataTypes/DataTypeFactory.h>
 #include <DataTypes/DataTypeObject.h>
+#include <DataTypes/DataTypeObjectDeprecated.h>
 #include <DataTypes/Serializations/SerializationJSON.h>
 #include <DataTypes/Serializations/SerializationObjectTypedPath.h>
 #include <DataTypes/Serializations/SerializationObjectDynamicPath.h>
 #include <DataTypes/Serializations/SerializationSubObject.h>
 #include <Columns/ColumnObject.h>
+#include <Common/CurrentThread.h>
 
 #include <Parsers/IAST.h>
 #include <Parsers/ASTLiteral.h>
@@ -511,13 +513,24 @@ static DataTypePtr createObject(const ASTPtr & arguments, const DataTypeObject::
 
 static DataTypePtr createJSON(const ASTPtr & arguments)
 {
+    auto context = CurrentThread::getQueryContext();
+    if (!context)
+        context = Context::getGlobalContextInstance();
+
+    if (context->getSettingsRef().use_json_alias_for_old_object_type)
+    {
+        if (arguments && !arguments->children.empty())
+            throw Exception(ErrorCodes::BAD_ARGUMENTS, "Experimental Object type doesn't support any arguments. If you want to use new JSON type, set setting allow_experimental_json_type = 1");
+
+        return std::make_shared<DataTypeObjectDeprecated>("JSON", false);
+    }
+
     return createObject(arguments, DataTypeObject::SchemaFormat::JSON);
 }
 
 void registerDataTypeJSON(DataTypeFactory & factory)
 {
-    if (!Context::getGlobalContextInstance()->getSettingsRef().use_json_alias_for_old_object_type)
-        factory.registerDataType("JSON", createJSON, DataTypeFactory::Case::Insensitive);
+    factory.registerDataType("JSON", createJSON, DataTypeFactory::Case::Insensitive);
 }
 
 }

src/DataTypes/DataTypeObjectDeprecated.cpp

@@ -78,10 +78,6 @@ static DataTypePtr create(const ASTPtr & arguments)
 void registerDataTypeObjectDeprecated(DataTypeFactory & factory)
 {
     factory.registerDataType("Object", create);
-    if (Context::getGlobalContextInstance()->getSettingsRef().use_json_alias_for_old_object_type)
-        factory.registerSimpleDataType("JSON",
-            [] { return std::make_shared<DataTypeObjectDeprecated>("JSON", false); },
-            DataTypeFactory::Case::Insensitive);
 }
 
 }

tests/queries/0_stateless/03230_json_alias_new_old_types.reference

@@ -0,0 +1,2 @@
+{"a":"42"}	JSON
+{"a":42}	Object(\'json\')

tests/queries/0_stateless/03230_json_alias_new_old_types.sql

@@ -0,0 +1,8 @@
+set allow_experimental_object_type=1;
+set allow_experimental_json_type=1;
+set use_json_alias_for_old_object_type=0;
+select materialize('{"a" : 42}')::JSON as json, toTypeName(json);
+set use_json_alias_for_old_object_type=1;
+select '{"a" : 42}'::JSON as json, toTypeName(json);
+select '{"a" : 42}'::JSON(max_dynamic_paths=100) as json, toTypeName(json); -- {serverError BAD_ARGUMENTS}
+