[FLINK-13690] Connectors/JDBC LookupFunction getFieldFromResultSet BUG

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 1.8.0, 1.9.0
• Component/s: Connectors / JDBC
• Labels: pull-request-available
• Assignee: molsion mo
• Reporter: molsion mo
• Created: 12/Aug/19 09:13
• Updated: 13/Aug/19 04:08
• Resolved: 13/Aug/19 04:07

Description

JDBCUtils.getFieldFromResultSet(int index, int type, ResultSet set) 

this method have a bug,  ResultSet.wasNull() reports whether the last column read had a value of SQL NULL, NOT the current column , when  one colums's value is null then all colums value behind it  will be null , even if they are not null

bug scene:

1. I want to join a dimension table,  column is

Id (INT), ProjectType(INT), Desp(VARCHAR),ProjectName(VARCHAR)

 

2. select from database table is

{"Id": 10, "ProjectType":100,"Desp":NULL,"ProjectName":"ProjectName"}

 

3. org.apache.flink.api.java.io.jdbc.JDBCLookupFunction#convertToRowFromResultSet return the row is 

{"Id": 10, "ProjectType":100,"Desp":NULL,"ProjectName":NULL}

beause  JDBCUtils.getFieldFromResultSet(int index, int type, ResultSet set)  when index = 3, ResultSet.wasNull is true, then value of column ProjectName is null

 

this operator will influence next opertator , then i can not get the column  ProjectName.

 

Bug Fix:

org.apache.flink.api.java.io.jdbc.JDBCUtils#getFieldFromResultSet can fix NULL judge to fix this bug

 

Issue Links

• is duplicated by: FLINK-13490 Fix if one column value is null when reading JDBC, the following values are all null
• links to: GitHub Pull Request #9418