confluentinc/ksql

avg should return null when no row is aggregated

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#9,752 opened on Jan 4, 2023

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 (1 comment) (0 reactions) (0 assignees)Java (5,739 stars) (1,048 forks)batch import
enhancementgood first issue

Description

Is your feature request related to a problem? Please describe. avg returns 0.0 instead of NULL when no row is aggregated. However, IMHO, NULL is preferable because 0.0 means nothing. In addition, other projects like apache spark return null in this case. What do you think?

Describe the solution you'd like avg should return null when no row is aggregated.

Describe alternatives you've considered

Additional context

Contributor guide

Tech stack
javasql
Domain
database
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
needs maintainer response
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Java knowledgeSQL aggregate functionsksqlDB source code navigation
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
45
Research direction
Investigate the implementation of the AVG aggregate function in the ksqlDB codebase. Look for the method that computes the average and check how it handles zero rows. Consider modifying it to return null instead of 0.0 when no rows are aggregated. Review existing tests for AVG to understand expected behavior and add new tests for the null case.
avg should return null when no row is aggregated · confluentinc/ksql#9752 | Good First Issue