Problem with M function Text.NewGUID()

[Sam88]

Hi!

we would like to assign a different GUID for each Row in a Query.

I've tried the function Text.NewGUID() but there are some strange behaviours.

I noticed that:

-  in Query Editor it's mandatory to put the column with the GUID as last after an index;

- if I merge or append the query with the ID with another one the system set the same GUID for every row;

- when the query it's applied the system set the same GUID for every row as in Report as in Data View.

Have someone experienced the same issue?

thanks,

have a nice day

Samuele

[v-shex-msft]

Hi @Sam88,

It is an known issue which consulted form product team, you can refer to below link to know more about this:

Problem with Text.NewGUID() M Language

BTW, if you only input Text.NewGUID() to custom column formula, it seem return the static value, but if you add some calculation to this query, it will return the dynamic value.

Regards,

Xiaoxin Sheng

[MarcelBeug · Accepted solution]

I don't fully understand your issues, but I recognize the duplicate GUIDs.

It must have something to do with lazy evaluation (Power Query code is evaluated only if absolutely required; in this case it looks like one time evaluation of Text.NewGuid is regarded sufficient to generate GUID's for multiple rows, which is - of course - wrong).

Maybe somebody will come up with a better solution, but a working workaround is to create the new Guid as a nested table and take the value of Column1, row 0:

let
    Source = #table(type table[ID = Int64.Type],List.Zip({{1..10}})),
    #"Added Custom" = Table.AddColumn(Source, "GUID", each #table(1,{{Text.NewGuid()}})[Column1]{0}, type text)
in
    #"Added Custom"

Edit: beware that new GUID's will be created with every refresh of the query.