[GitHub] [shardingsphere] huanghao495430759 commented on issue #8605: table for unconfigured "SELECT t.*, t2.col FROM t LEFT JOIN t2" not work

Fri, 15 Jan 2021 02:32:49 -0800 


huanghao495430759 commented on issue #8605:
URL: https://github.com/apache/shardingsphere/issues/8605#issuecomment-760812843


   > when I used @iblilife's sql:
   > `SELECT a.*, b.id FROM table_a a LEFT JOIN table_b b ON (a.id = b.id)`;
   > and shardingsphere-5.0.0-RC1-SNAPSHOT have the same proplem.
   > 
   > when shardingsphere create ShardingSpherePreparedStatement
   > I think the bug may be at SchemaBuilder.java line 70:
   > 
![image](https://user-images.githubusercontent.com/34728144/104438647-2b69ad00-55cb-11eb-9750-964239b63f6e.png)
   > 
   > when load unconfig tables MeataData,it only init TableMetaData(), but 
doesn't load table columns,
   > so when doQuery in :
   > 
`->org.apache.shardingsphere.driver.jdbc.core.statement.ShardingSpherePreparedStatement#execute
 
->org.apache.shardingsphere.driver.jdbc.core.statement.ShardingSpherePreparedStatement#createExecutionContext
 
->org.apache.shardingsphere.driver.jdbc.core.statement.ShardingSpherePreparedStatement#createLogicSQL
 
->org.apache.shardingsphere.infra.binder.SQLStatementContextFactory#newInstance 
->new SelectStatementContext 
->org.apache.shardingsphere.infra.binder.segment.select.projection.engine.ProjectionsContextEngine#createProjectionsContext
 
->org.apache.shardingsphere.infra.binder.segment.select.projection.engine.ProjectionsContextEngine#getProjections
 
->org.apache.shardingsphere.infra.binder.segment.select.projection.engine.ProjectionEngine#createProjection(final
 Collection<SimpleTableSegment> tableSegments, final ShorthandProjectionSegment 
projectionSegment) 
->org.apache.shardingsphere.infra.binder.segment.select.projection.engine.ProjectionEngine#getShorthandColumns`
   > when get ShorthandColumns, table columns is empty
   > 
![image](https://user-images.githubusercontent.com/34728144/104438411-efcee300-55ca-11eb-9433-925d656fc4b5.png)
   > so after ShardingSpherePreparedStatement#execute,
   > and handle resultSet
   > 
![image](https://user-images.githubusercontent.com/34728144/104438860-7257a280-55cb-11eb-9e63-938cc9d59004.png)
   > 
`->org.apache.ibatis.executor.resultset.DefaultResultSetHandler#handleResultSets
 
->org.apache.ibatis.executor.resultset.DefaultResultSetHandler#getFirstResultSet
 ->org.apache.ibatis.executor.resultset.ResultSetWrapper#ResultSetWrapper() 
->org.apache.shardingsphere.driver.jdbc.core.resultset.ShardingSphereResultSetMetaData#getColumnCount
 
->org.apache.shardingsphere.infra.binder.segment.select.projection.ProjectionsContext#getExpandProjections`
   > 
![image](https://user-images.githubusercontent.com/34728144/104439228-d9755700-55cb-11eb-985e-20642a7e5a6c.png)
   > 
![image](https://user-images.githubusercontent.com/34728144/104439686-5a345300-55cc-11eb-872c-43856b826311.png)
   > 
   > in this code, ShorthandProjection actual columns is empty,so after 
getExpandProjections(), columnCount is only 1
   > 
![image](https://user-images.githubusercontent.com/34728144/104439787-7c2dd580-55cc-11eb-99c9-ca2a7525045d.png)
   > 
   > 
![image](https://user-images.githubusercontent.com/34728144/104440276-1b52cd00-55cd-11eb-96d7-6951241b3559.png)
   > and ResultSet only get one column。
   > 
   > so I think bug maybe at
   > 
`->org.apache.shardingsphere.infra.metadata.schema.builder.SchemaBuilder#appendRemainTables
 line 70`
   > 
![image](https://user-images.githubusercontent.com/34728144/104441089-32de8580-55ce-11eb-82d2-7e73196a7dbd.png)
   > shardingsphere must be load remain table MetaData when System start.
   
   @strongduanmu
   @tristaZero 


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