USE OF MOD ON FILE STATEMENTS.

When outputting column headings on flat files, consider outputting them in a previous data step rather than testing “IF _N_=1” if this test will be processed many times. The savings in CPU are relatively small for this test, but if a large amount of observations are being processed then the savings may become significant.

e.g.

Data _Null_;
    File Output;
    Retain Tab ‘05’x;
    Put ‘District’ Tab ‘Account’ Tab ‘Blah’ Tab ‘Blah’ Tab ‘Blah’;

Data _Null_;
    Retain Tab ‘05’x;
    Merge BigFile1(In=In1)
          EvenBigr(In=In2);
    By District Account;
    If In1 and In2 and Blah1=Blah2;
    File Output Mod;
    Put District Tab Account Tab Blah1 Tab Blah2 Tab Blah3;
Run;