[IMPALA-1802] Impala produces incorrect count(distinct xxx) result with limit clause

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: Impala 2.1
• Fix Version/s: Impala 2.2
• Labels: correctness
• Assignee: Dimitris Tsirogiannis
• Reporter: Huifang Qin
• Created: 20/Feb/15 18:58
• Updated: 20/Dec/15 00:05
• Resolved: 10/Mar/15 20:22

Description

In a partitioned data table, Impala produced the following results. We would expect all these queries to return the same number, and hope this bug can be fixed.

select count(distinct ts) from data_table limit 10;
1978021

select count(distinct ts) from data_table limit 11;
2176581   

select count(distinct ts) from data_table limit 12;
2374214 

select count(distinct ts) from data_table limit 13;
2572205     (correct)

Compared to:

select count(distinct ts) from data_table;
2572205           

hive -e "select count(distinct ts) from data_table limit 10;"
2572205

Thanks,
Huifang