format() is a nondeterministic built-in string function... right?

Before I post a connect item regarding the lack of documentation about this, will someone confirm that I am not simply missing something here?

On the docs page where format is listed as a string function:


"All built-in string functions are deterministic." - String Functions (Transact-SQL)

There is also no mention of format being nondeterministic on related pages:

• Deterministic and Nondeterministic Functions

• FORMAT (Transact-SQL)

However, when attempting to create a persisted computed column:

create table t (date_col date); 
insert into t values (getdate());
alter table t add date_formatted_01 as format(date_col,'YYYY') persisted;

Returns the following error:


Computed column 'date_formatted_01' in table 't' cannot be persisted because the column is non-deterministic.

The documentation states that


If the culture argument is not provided, the language of the current
session is used.

but adding a culture argument doesn't change things

This also fails

alter table t add date_formatted_02 as format(date_col, 'd', 'en-US' ) persisted

rextester demo: http://rextester.com/ZMS22966

dbfiddle.uk demo: http://dbfiddle.uk/?rdbms=sqlserver_next&fiddle=7fc57d1916e901cb561b551af144aed6

The FORMAT documentation has now been updated (in response to your Connect item) to say:


The FORMAT function is nondeterministic.

Likewise, String Functions (Transact-SQL) now includes:


All built-in string functions except FORMAT are deterministic.

StackExchange Database Administrators Q#174739, answer score: 7