[DRILL-7935] Error: Hash join does not support schema changes in probe side.

• Type: Bug
• Status: Open
• Priority: Critical
• Resolution: Unresolved
• Affects Version/s: 1.18.0
• Assignee: Unassigned
• Reporter: Raúl
• Created: 26/May/21 13:39
• Updated: 19/Jul/22 08:49

Description

Let's see if someone can help us, we have a problem:

We have a collection in mongo with 58,948 documents, in which a field of the collection is null in 58,270 and with value (not null) 714. In a select, when we join on that collection, it returns the following error:

SQL Error: UNSUPPORTED_OPERATION ERROR: Hash join does not support schema changes in probe side.
Prior schema :  

BatchSchema [fields=[[`CITY_CODE` (VARCHAR:OPTIONAL)], [`COMPANY_CODE` (INT:OPTIONAL)], [`LOCATION_CODE0` (VARCHAR(65535):OPTIONAL)]], selectionVector=NONE]
New schema : 
BatchSchema [fields=[[`CITY_CODE` (VARCHAR:OPTIONAL)], [`COMPANY_CODE` (VARCHAR:OPTIONAL)], [`LOCATION_CODE0` (VARCHAR(65535):OPTIONAL)]], selectionVector=NONE]
 
Unsupported schema change
Fragment: 0:0

The problem that I observe is that when the field has so many nulls, it considers it INT, and when it crosses it, it sees that a value is varchar and that is when it gives the error.

1.) How can I solve this problem? I have changed different parameters regarding mongo and nothing makes it work
2.) Why does Drill consider null to be an int? It should not consider it as varchar.
If I make a select only of the COMPANY_CODE field and I try to sort it, it gives me the following error:

SQL Error: INTERNAL_ERROR ERROR: You tried to write a VarChar type when you are using a ValueWriter of type NullableIntWriterImpl.
Fragment: 0:0
Please, refer to logs for more information.

Thank you!!

Issue Links

• relates to: DRILL-8190 Mongo query: "Schema change not currently supported for schemas with complex types"