Which load script would execute faster (less execution time)?

[#1]

I want to create 2 fields with the exact same data (for different transformation later), and I can think of 2 ways of doing so:

Load Script 1:

    Load

          applymap ('map_table1', map_field1)    as field1

          applymap ('map_table1', map_field1)    as field2

    From [C\...] (qvd);

Load Script 2:

    Load

        *,

          field1 as field2;

    Load

          applymap ('map_table1', map_field1)    as field1

    From [C\...] (qvd);

Which load script would run faster? Would there be any difference between the results of the 2 load scripts?

[maxgro · Accepted solution]

the one with 2 applymap

[swuehl]

Another approach could also be

MAP field1, field2 USING map_table1;

    Load

          map_field1    as field1,

          map_field1    as field2

    From [C\...] (qvd);

I've learned to be cautious with general answers to performance questions. It may depend on different properties of the data set.

Just test with your own data.

[#4]

Perform the load test couple of times and you will get the which script get better.

I think Script 2 works fast because you have only one mapping load.