What is the use of “create essential data” in system update via hac in SAP HYBIRS?

While system update from hac, we have three options

1. Update running system
2. Create essential data
3. localised type

Can anyone please explain what’s the use of all these three fields and why do we prefer unchecking “create essential data” most of the times?

A couple of links related to what essential data is:

• https://help.sap.com/docs/SAP_COMMERCE/4c33bf189ab9409e84e589295c36d96e/8ad2f0a7866910149c31803942c91149.html?locale=en-US
• https://help.sap.com/docs/SAP_COMMERCE/3fb5dcdfe37f40edbac7098ed40442c0/9236d781bd6a4330ad12dbc3b8880e77.html?locale=en-US

What do those 3 items do:

1. Update DB schema + type meta data in the DB for this Hybris environment
2. Load/reload the configured essential/core data sets into the DB
3. Load localisation file contents into the DB: localisation for types/attributes for example

In my view the essential/core data should always be safe to load during a system update, including in production. It is intended to be items that are essential for correct operation of the system & should not vary.

If there are items in the essential data that are being updated at runtime & essential data overwrites that - you either have incorrectly assigned some imports to essential data (instead of project/sample data), or you have somebody doing runtime stuff that they should not. Data that is intended for runtime maintenance should be in project/sampledata (which can be viewed as a starting point data set for the lower environments such as dev) - these data sets generally should not be run during an update, especially in production.