[IMPALA-11301] Extreme cardinality estimations if NDV=1

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 4.0.0, Impala 4.1.0
• Fix Version/s: Impala 4.2.0, Impala 4.1.1
• Component/s: Frontend
• Epic Color: ghx-label-5
• Assignee: Csaba Ringhofer
• Reporter: Csaba Ringhofer
• Created: 18/May/22 15:42
• Updated: 23/Aug/22 05:52
• Resolved: 20/May/22 15:07

Description

if ndv of string_col == 1, then string_col != "something const" will have a selectivity of 0, leading to a cardinality of 1 regardless of number of rows

This issue was introduced in IMPALA-10677

Issue Links

• is broken by: IMPALA-10677 Set selectivity of "!="