[DRILL-884] Query used to derive result set metadata for Tableau's "Custom SQL" does not run

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: 0.4.0
• Component/s: Execution - Flow
• Labels: Tableau
• Assignee: Unassigned
• Reporter: George Chow
• Created: 31/May/14 01:44
• Updated: 20/Jun/14 20:28
• Resolved: 20/Jun/14 20:28

Description

The following style of query is used by Tableau to derive the metadata of a custom SQL:

From Tableau's protocol server log:

2014-05-30 18:35:39.718 (-,-,-,-) 0ea0: ODBCProtocol::ReadMetadataImpl: Attempting to read metadata from the prepared / executed query result set.
2014-05-30 18:35:39.718 (-,-,-,-) 0ea0: ODBCProtocolImpl::ReadMetadataImpl: Reading metadata using a prepared statement.
2014-05-30 18:35:39.718 (-,-,-,-) 0ea0: <QUERY protocol='0367b1f0'>
2014-05-30 18:35:39.718 (-,-,-,-) 0ea0: SELECT *
2014-05-30 18:35:39.718 (-,-,-,-) 0ea0: FROM (
2014-05-30 18:35:39.718 (-,-,-,-) 0ea0:   select * from dfs.`default`.`/opt/drill/raw-files/click1.json`
2014-05-30 18:35:39.718 (-,-,-,-) 0ea0: ) `TableauSQL`
2014-05-30 18:35:39.718 (-,-,-,-) 0ea0: WHERE (0 = 1)
2014-05-30 18:35:39.718 (-,-,-,-) 0ea0: </QUERY>
2014-05-30 18:35:39.718 (-,-,-,-) 0ea0: ODBCProtocolImpl::ReadMetadataImpl: SQLPrepare failed. Reading metadata using an executed query.
2014-05-30 18:35:47.640 (-,-,-,-) 0ea0: ODBCProtocolImpl::ReadMetadataImpl: No columns were reported!

Extracting the query to run inside sqlline shows the problem:

 
0: jdbc:drill:zk=localhost:5181> select * from (select * from dfs.`default`.`/opt/drill/raw-files/click1.json`) `TableauSQL` where (0=1);
+--+ 
| | 
+--+ 
+--+ 
No rows selected (9.059 seconds) 

Issue Links

• relates to: DRILL-1026 Tableau generated metadata query does not return metadata for multi-region HBase table
• relates to: DRILL-1029 select column from a `select *` sub-query fails for schema-less file