When we change PCI in LTE is it mandatory to change rootseqindex?

Hello All,
When we change PCI in LTE is it mandatory to change rootseqindex?
What is the impact if we don’t change it?

PCI is of DL, rootseqind is of UL, no relationship, no need to change together.

Usually when you change PCI you should have a look at RACH root sequence index too.

Why? Is there any relation why we need to take care of RSI with PCI?

Because rules of populating rach root sequence index are most of the times based on PCI plan.