Multiple persons several cases

[EDsCODE]

@paolodamico and I spent an afternoon sifting through person data of various teams to understand how teams were using posthog.identify, specifically when email was provided, and if the problem with seemingly multiple copies of a person was a bug in implementation or an issue with how users were calling the function. We discovered several cases:

1. Flawless usage where persons are never duplicated against emails (example)
2. Duplicated persons where it seemed as though a company was calling posthog.identify on an incrementing ID which was causing multiples of a person. Here's an example
3. Duplicated persons across organization ids which is an expected side effect of signing up on different deployments explained here
4. Duplicated persons where the distinct_ids look like anonymous ids we generate. Here's an example of a person with multiple rows and the distinct_ids associated with them. Notice that none of the distinct_ids seem to be user passed in

*Duplicated means there are several person rows that all seem like they should be the same person based on their properties (email mainly)

Will continue adding findings/fixes to this thread

[EDsCODE]

@kpthatsme tagging you so you have a heads up of some reasons for the duplicates

[paolodamico]

Worth referencing https://github.com/PostHog/internal/issues/243 which explains the main culprit of duplicated persons, and the path forward of how we'll address it.

[posthog-bot]

This issue hasn't seen activity in two years! If you want to keep it open, post a comment or remove the stale label – otherwise this will be closed in two weeks.

[posthog-bot]

This issue was closed due to lack of activity. Feel free to reopen if it's still relevant.