PostHog/posthog

Bug: In Cohorts, the 'set' operator filters in null values for person properties

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#29,916 建立於 2025年3月13日

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描述

Bug description

In Cohorts, 'set' operator filters in null values for person properties.

Expected outcome

  • 'set' should filter out null values
  • 'not set' should include null values

Using Have the property vs Does not have the property doesn't solve this because we want to filter out users who have the property but with a null value.

In filters, 'not set' filters in 'null while 'set' filters it out. This means there's an inconsistency with how we handle this in Cohorts.

How to reproduce

  1. Create a cohort and filter by having a person property that you know some users have null for and select 'set'
  2. notice the list of users includes users with 'null'

You can test with this cohort: https://us.posthog.com/project/53137/cohorts/122367

Additional context

From: https://posthoghelp.zendesk.com/agent/tickets/27021

Debug info

null

貢獻者指南

技術棧
python
領域
backend
議題類型
bug
難度面向新貢獻者的預計實作難度，1 表示很小改動，5 表示專家級工作。
3
預計時間有經驗貢獻者完成調查、實作、測試並準備 pull request 的粗略時間範圍。
1-3 hours
活動狀態議題目前的可參與程度：新鮮、活躍、陳舊、阻塞或等待維護者輸入。
active
清晰度議題是否清楚說明預期改動、驗收標準和下一步。
clear
前置要求
Understanding of cohort filteringSQL null handling knowledgeFamiliarity with PostHog property filters
新手友善度1-100 的估計分數，表示該議題對首次貢獻者的友善程度。
50
研究方向
Investigate the cohort filtering logic in the backend, specifically the handling of null values for person properties. Look at the query building code for cohort definitions, likely in the `posthog/models/cohort` or `posthog/queries` directory. Compare the `set` and `not set` operators' behavior with person property filters. Ensure that the SQL query for 'set' excludes null values and 'not set' includes them. Refer to the existing filter logic in `PropertyFilter` classes.