query [select * from aly_test where id =ALL(select 1);] success but explain failed

[irene-coming]

• dble version：
  5.6.29-dble-9.9.9.9-359645c-20181029082136

• preconditions ：
  no

• configs：

schema.xml

<table name="aly_test" dataNode="dn1,dn2,dn3,dn4" rule="hash-four" />

• steps：
  step1. execute prepare sqls with dble:

mysql> drop table if exists aly_test;
Query OK, 0 rows affected (0.00 sec)

mysql> create table aly_test(id int, name varchar(20));
Query OK, 0 rows affected (0.03 sec)

mysql> insert into aly_test values(1,'a'),(2,'b'),(5,null);
Query OK, 3 rows affected (0.00 sec)

step2. execute sql with dble:

mysql> explain select * from aly_test where id =ALL(select 1);
ERROR 1105 (HY000): table node buildOwn exception! Error:columnValue:{ALL_SUB_QUERY_RESULTS} Please eliminate any quote and non number within it.
mysql> select * from aly_test where id =ALL(select 1);
+------+------+
| id   | name |
+------+------+
|    1 | a    |
+------+------+
1 row in set (0.00 sec)

• expect result：
  1. step2. query "explain xxx;" success
• real result：
  1.step2 "explain xxx" gets error
• supplements：
  1.dble.log segment:

2018-11-01 02:38:43.906  INFO [BusinessExecutor0] (com.actiontech.dble.route.impl.DefaultRouteStrategy.parserSQL(DefaultRouteStrategy.java:37)) - routeNormalSqlWithAST
com.alibaba.druid.sql.parser.ParserException: syntax error, error in :'aly_test', expect IDENTIFIER, actual IDENTIFIER pos 8, line 1, column 9, token IDENTIFIER aly_test
        at com.alibaba.druid.sql.parser.SQLParser.printError(SQLParser.java:284) ~[druid-1.1.10.jar:1.1.10]
        at com.alibaba.druid.sql.parser.SQLStatementParser.parseStatementList(SQLStatementParser.java:426) ~[druid-1.1.10.jar:1.1.10]
        at com.alibaba.druid.sql.parser.SQLStatementParser.parseStatement(SQLStatementParser.java:2738) ~[druid-1.1.10.jar:1.1.10]
        at com.actiontech.dble.route.impl.DefaultRouteStrategy.parserSQL(DefaultRouteStrategy.java:35) [dble-9.9.9.9.jar:?]
        at com.actiontech.dble.route.impl.DefaultRouteStrategy.routeNormalSqlWithAST(DefaultRouteStrategy.java:73) [dble-9.9.9.9.jar:?]
        at com.actiontech.dble.route.impl.AbstractRouteStrategy.route(AbstractRouteStrategy.java:50) [dble-9.9.9.9.jar:?]
        at com.actiontech.dble.route.RouteService.route(RouteService.java:112) [dble-9.9.9.9.jar:?]
        at com.actiontech.dble.server.handler.ExplainHandler.getRouteResultset(ExplainHandler.java:159) [dble-9.9.9.9.jar:?]
        at com.actiontech.dble.server.handler.ExplainHandler.handle(ExplainHandler.java:65) [dble-9.9.9.9.jar:?]
        at com.actiontech.dble.server.ServerQueryHandler.query(ServerQueryHandler.java:73) [dble-9.9.9.9.jar:?]
        at com.actiontech.dble.net.FrontendConnection.query(FrontendConnection.java:319) [dble-9.9.9.9.jar:?]
        at com.actiontech.dble.net.FrontendConnection.query(FrontendConnection.java:335) [dble-9.9.9.9.jar:?]
        at com.actiontech.dble.net.handler.FrontendCommandHandler.handleData(FrontendCommandHandler.java:77) [dble-9.9.9.9.jar:?]
        at com.actiontech.dble.net.handler.FrontendCommandHandler.handle(FrontendCommandHandler.java:55) [dble-9.9.9.9.jar:?]
        at com.actiontech.dble.net.handler.FrontEndHandlerRunnable.run(FrontEndHandlerRunnable.java:44) [dble-9.9.9.9.jar:?]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [?:1.8.0_121]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [?:1.8.0_121]
        at java.lang.Thread.run(Thread.java:745) [?:1.8.0_121]
2018-11-01 02:38:43.907  INFO [BusinessExecutor0] (com.actiontech.dble.server.handler.ExplainHandler.getRouteResultset(ExplainHandler.java:170)) - ServerConnection [id=8, schema=mytest2, host=127.0.0.1, user=test,txIsolation=3, autocommit=true, schema=mytest2]aly_test error:java.sql.SQLSyntaxErrorException: syntax error, error in :'aly_test', expect IDENTIFIER, actual IDENTIFIER pos 8, line 1, column 9, token IDENTIFIER aly_test

/label ~BUG

[FlyingMao]

verified version： 5.6.29-dble-9.9.9.9-a68f557-20181119123440