[KYLIN-5787] Use t-digest as spark percentile_approx function

• Type: Improvement
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 5.0-beta
• Fix Version/s: 5.0-beta
• Component/s: Job Engine, Query Engine
• Assignee: pengfei.zhan
• Reporter: pengfei.zhan
• Due: 31/Mar/24
• Created: 30/Mar/24 04:10
• Updated: 10/Apr/24 00:55
• Resolved: 10/Apr/24 00:55

Description

The underlying implementation of the percentile_approx function in KYLIN is the open-source t-digest.

The underlying implementation of the percentile_approx function in spark is spark's own PercentileDigest (based on QuantileSummaries).
Different implementations lead to different results.