Is it possible to keep existing ECID when changing cookie domain?

[VishnuPriya98]

Hi All,
I need some clarification about ECID cookie behavior. Currently, ECID cookies are set at the subdomain level, and we are planning to update the configuration so that they are set at the root domain for persistence across subdomains.

My doubt is: if an ECID already exists on a user’s browser, is it possible to prevent a new ECID from being generated when we change the cookie domain? Or is there any other way to migrate cookies without affecting previous users? If a new ECID is always created, is the only option to use visitor.setCustomerIDs() for logged-in users?

Has anyone implemented this type of migration, and what approach worked best?

[Jennifer_Dungan]

Technically, if the user is still identified by the Demdex server, they should still get the same ECID value. Since the identification is for the user against the Visitor ID service itself.

While some users might get lost, they are likely going to get lost anyway due to the way their browser is processing third-party cookies.

I would test out scenarios first to see if you will even have an issue...