[SPARK-19350] Cardinality estimation of Limit and Sample

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.2.0
• Component/s: SQL
• Assignee: Zhenhua Wang
• Reporter: Zhenhua Wang
• Created: 24/Jan/17 12:57
• Updated: 07/Mar/17 05:46
• Resolved: 07/Mar/17 05:46

Description

Currently, LocalLimit/GlobalLimit/Sample propagates the same row count and column stats from its child, which is incorrect.
We can get the correct rowCount in Statistics for Limit/Sample whether cbo is enabled or not. And column stats should not be propagated because we don't know the distribution of columns after Limit or Sample.

Issue Links

• links to: [Github] Pull Request #16696 (wzhfy)