[DRILL-1692] select * on mongo join returns invalid results

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.6.0
• Fix Version/s: 0.8.0
• Component/s: Storage - MongoDB

Environment

select * queries on mongo joins

• Assignee: Parth Chandra
• Reporter: AnilKumar B
• Created: 12/Nov/14 06:09
• Updated: 04/Mar/15 06:01
• Resolved: 04/Mar/15 06:01

Description

select * on mongo joins gives improper results. Need to modify the schema handling logic in the case of 'select *' logic in MongoRecordReader.

For example when we fire a below query on mongo.employee.`join1` table, the results are as below.

SELECT * FROM mongo.employee.`join1` t1 JOIN mongo.employee.`join1` t2 ON t1.`employee_id` = t2.`employee_id`

sample documents in mongo.employee.`join1` table:

{ "employee_id" : 1 , "first_name" : "Anil"} { "employee_id" : 2 , "first_name" : "Kamesh"}

Results:

{ "employee_id" : 1 , "first_name" : "Anil"}	{ "employee_id" : 1 , "first_name" : "Anil"}
{ "employee_id" : 1 , "first_name" : "Anil"}	{ "employee_id" : 2 , "first_name" : "Kamesh"}
{ "employee_id" : 2 , "first_name" : "Kamesh"}	{ "employee_id" : 1 , "first_name" : "Anil"}
{ "employee_id" : 2 , "first_name" : "Kamesh"}	{ "employee_id" : 2 , "first_name" : "Kamesh"}

Issue Links

• is related to: DRILL-1514 Joins are not working with mongo
• is related to: DRILL-2352 MongoDB join queries can't select fields