KQL: mv-expand OR bag_unpack equivalent command to convert a list to multiple columns - azure-log-analytics

Question

According to mv-expand documentation:
Expands multi-value array or property bag.
mv-expand is applied on a dynamic-typed column so that each value in the collection gets a separate row. All the other columns in an expanded row are duplicated.
Just like the mv-expand operator will create a row each for the elements in the list -- Is there an equivalent operator/way to make each element in a list an additional column?
I checked the documentation and found Bag_Unpack:
The bag_unpack plugin unpacks a single column of type dynamic by treating each property bag top-level slot as a column.
However, it doesn't seem to work on the list, and rather works on top-level JSON property.
Using bag_unpack (like the below query):
datatable(d:dynamic)
[
dynamic({"Name": "John", "Age":20}),
dynamic({"Name": "Dave", "Age":40}),
dynamic({"Name": "Smitha", "Age":30}),
]
| evaluate bag_unpack(d)
It will do the following:
Name Age
John 20
Dave 40
Smitha 30
Is there a command/way (see some_command_which_helps) I can achieve the following (convert a list to columns):
datatable(d:dynamic)
[
dynamic(["John", "Dave"])
]
| evaluate some_command_which_helps(d)
That translates to something like:
Col1 Col2
John Dave
Is there an equivalent where I can convert a list/array to multiple columns?
For reference: We can run the above queries online on Log Analytics in the demo section if needed (however, it may require login).

Answer 1

you could try something along the following lines
(that said, from an efficiency standpoint, you may want to check your options of restructuring the data set to begin with, using a schema that matches how you plan to actually consume/query it)
datatable(d:dynamic)
[
dynamic(["John", "Dave"]),
dynamic(["Janice", "Helen", "Amber"]),
dynamic(["Jane"]),
dynamic(["Jake", "Abraham", "Gunther", "Gabriel"]),
]
| extend r = rand()
| mv-expand with_itemindex = i d
| summarize b = make_bag(pack(strcat("Col", i + 1), d)) by r
| project-away r
| evaluate bag_unpack(b)
which will output:
|Col1 |Col2 |Col3 |Col4 |
|------|-------|-------|-------|
|John |Dave | | |
|Janice|Helen |Amber | |
|Jane | | | |
|Jake |Abraham|Gunther|Gabriel|

Answer 2

To extract key value pairs from text and convert them to columns without hardcoding the key names in query:
print message="2020-10-15T15:47:09 Metrics: duration=2280, function=WorkerFunction, count=0, operation=copy_into, invocationId=e562f012-a994-4fc9-b585-436f5b2489de, tid=lct_b62e6k59_prd_02, table=SALES_ORDER_SCHEDULE, status=success"
| extend Properties = extract_all(#"(?P<key>\w+)=(?P<value>[^, ]*),?", dynamic(["key","value"]), message)
| mv-apply Properties on (summarize make_bag(pack(tostring(Properties[0]), Properties[1])))
| evaluate bag_unpack(bag_)
| project-away message