SubQuery with ”select *“ may cause connection closed and StackOverflow

[yanhuqing666]

• dble version： all

• preconditions ：
  CREATE TABLE sharding_two_node (
  id int(11) NOT NULL,
  c_flag char(255) DEFAULT NULL,
  c_decimal decimal(16,4) DEFAULT NULL,
  PRIMARY KEY (id)
  ) ENGINE=InnoDB DEFAULT CHARSET=utf8;

• configs：

schema.xml

<table name="sharding_two_node" dataNode="dn1,dn2" rule="two_node_hash"/>

rule.xml

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE dble:rule SYSTEM "rule.dtd">
<dble:rule xmlns:dble="http://dble.cloud/">
    <tableRule name="two_node_hash">
        <rule>
            <columns>id</columns>
            <algorithm>two_node_hash</algorithm>
       </rule>
    </tableRule>
    <function name="two_node_hash" class="Hash">
        <property name="partitionCount">2</property>
	<property name="partitionLength">512</property>
    </function>
</dble:rule>

server.xml

-

• steps：
  step1. select count(*) from sharding_two_node where id = (select * from sharding_two_node where id =1);
• expect result：
  1.ERROR 1241 (HY000): Operand should contain 1 column(s)
• real result：
  1.ERROR 2006 (HY000): MySQL server has gone away
  2.dble will in dead loop and dble.log will throw StackOverflowError
• supplements：
  1.

/label ~BUG

[FlyingMao]

verified version:5.6.29-dble-9.9.9.9-046baf4-20180817023708