[IMPALA-6113] Skip row groups with predicates on NULL columns

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 2.10.0
• Fix Version/s: Impala 3.0, Impala 2.12.0
• Component/s: Backend
• Labels: ramp-up
• Target Version: Product Backlog
• Epic Color: ghx-label-6
• Assignee: Gabor Kaszab
• Reporter: Lars Volker
• Created: 26/Oct/17 22:49
• Updated: 24/Feb/18 00:29
• Resolved: 05/Feb/18 13:32

Description

Column chunks that only contain NULL values don't have their min_value and max_value fields populated and as a result we cannot skip row groups based on predicates on such columns. IMPALA-5061 added support to populate the null_count in statistics, allowing us to detect column chunks that only contain NULLs. We should use that information to skip row groups if the predicate allows us to.

Issue Links

• is a child of: IMPALA-4989 Improve filtering based on parquet::Statistics