[HIVE-11266] count(*) wrong result based on table statistics for external tables

• Type: Bug
• Status: Closed
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 1.1.0
• Fix Version/s: 3.0.0
• Target Version/s: 2.4.0, 3.0.0
• Assignee: Jesús Camacho Rodríguez
• Reporter: Simone Battaglia
• Created: 15/Jul/15 10:11
• Updated: 27/Feb/24 22:23
• Resolved: 09/Oct/17 20:18

Description

Hive returns wrong count result on an external table with table statistics if I change table data files.

This is the scenario in details:
1) create external table my_table (...) location 'my_location';
2) analyze table my_table compute statistics;
3) change/add/delete one or more files in 'my_location' directory;
4) select count(*) from my_table;

In this case the count query doesn't generate a MR job and returns the result based on table statistics. This result is wrong because is based on statistics stored in the Hive metastore and doesn't take into account modifications introduced on data files.

Obviously setting "hive.compute.query.using.stats" to FALSE this problem doesn't occur but the default value of this property is TRUE.

I thinks that also this post on stackoverflow, that shows another type of bug in case of multiple insert, is related to the one that I reported:
http://stackoverflow.com/questions/24080276/wrong-result-for-count-in-hive-table

Issue Links

• is related to: HIVE-27409 Iceberg: table with EXTERNAL type can not use statistics to optimize the query