Statistics
https://play.clickhouse.com/play?user=play#c2VsZWN0IAp0b1N0YXJ0T2ZIb3VyKGNoZWNrX3N0YXJ0X3RpbWUpIGFzIGQsCmNvdW50KCksICBncm91cFVuaXFBcnJheShwdWxsX3JlcXVlc3RfbnVtYmVyKSwgIGFueShyZXBvcnRfdXJsKQpmcm9tIGNoZWNrcyB3aGVyZSAnMjAyMi0wNi0wMScgPD0gY2hlY2tfc3RhcnRfdGltZSBhbmQgdGVzdF9uYW1lIGxpa2UgJyUwMjQ5MV9wYXJ0X2xvZ19oYXNfdGFibGVfdXVpZCUnIGFuZCB0ZXN0X3N0YXR1cyBpbiAoJ0ZBSUwnLCAnRkxBS1knKSBncm91cCBieSBkIG9yZGVyIGJ5IGQgZGVzYw==

Some times there are not output from requests.
{
                const auto & deps_mv = name_deps[command.column_name];
                if (!deps_mv.empty())
                {
                    throw Exception(
                        "Trying to ALTER DROP column " + backQuoteIfNeed(command.column_name) + " which is referenced by materialized view "
                            + toString(deps_mv),
                        ErrorCodes::ALTER_OF_COLUMN_IS_FORBIDDEN);
                }
            }
            dropped_columns.emplace(command.column_name);
        }
        else if (command.type == AlterCommand::RESET_SETTING)
        {
            for (const auto & reset_setting : command.settings_resets)
            {
                if (!settings_from_storage->has(reset_setting))
                    throw Exception(ErrorCodes::BAD_ARGUMENTS, "Cannot reset setting '{}' because it doesn't exist for MergeTree engines family", reset_setting);
            }
        }
        else if (command.isRequireMutationStage(getInMemoryMetadata()))
        {
            
            
            if (columns_alter_type_forbidden.contains(command.column_name))
                throw Exception("ALTER of key column " + backQuoteIfNeed(command.column_name) + " is forbidden",
                    ErrorCodes::ALTER_OF_COLUMN_IS_FORBIDDEN);
            if (command.type == AlterCommand::MODIFY_COLUMN)
            {
                if (columns_alter_type_check_safe_for_partition.contains(command.column_name))