Can proc sort returns different results in different runs for the same data.

[phadnismukta]

I have a data with zip code and acc_nbr... when I sorted the data by zip code on different days, got same acct_nbr on different positions in the output data. Is it possible?

[Reeza]

It’s possible...one way would be if you had ties in the data and they were sorted differently previously to this sort. So you have a different data set order passed to the proc sort with ties. If you have ties it’s best to do a double sort,with the first sort using an extra variable to control the order. 

if you’re running the exact same program again, it’s unlikely. and I’d  guess 99% of cases are some form of user error - like above. 

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@phadnismukta wrote:

I have a data with zip code and acc_nbr... when I sorted the data by zip code on different days, got same acct_nbr on different positions in the output data. Is it possible?

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[Patrick]

If you only sort by zip_number and not also by account_number within a zip number then yes, nothing will control the order of the account_numbers.

If your source table is a SAS data set (and not a database table) then using proc sort option EQUALS will return rows in the same "sub-" order as they were in the source table.

[Kurt_Bremser]

On top of what others said, certain means of storage (SPDS) might also influence the outcome of a sort.

See Maxim 31. Take control and force any order you need.