In CRM dynamics 2016 version 8.* the maximum amount calculated fields was 10 for each entity.
Is this changed in version 9.0? Or is this still max 10?
Regarding docs.microsoft.com/.../calculated-rollup-attributes its still 10, yes.
The document you are referring to is posted on 10/31/2017.
Is this document still up to date with the introduction of version 9.0?
I think there is no limit in version 9.0 , the limit is for Saved queries, charts, and visualizations can have a maximum of 10 unique calculated fields ,check here under Calculated fields considerations
Calculated fields need asynchronous jobs to be run every hour to calculate value.. which will take more resources if there is no limit on creating calculating fields, and this will decrease performance of CRM system, that's why there is limit of only 10 fields per entity. If you are using On-permise CRM you could change this limit, but it is totally UNSUPPORTED and not recommend option.
In case, if you need more than 10 calculated fields on entity, you need to go with different approach, e.g. creating report to show those calculations when required or some custom HTML web resources.
hope this will help..
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