The size of files after Proc append

[CC13]

Hi all,

I used proc append to add observations from one sas data set to the end of another sas data set. However, I noticed the size of new dataset is much bigger than the sum of three adding data sets. I thought the size should be around the sum of three. Is there something wrong with the code?

data d.rat15to17; set d.rat15; run;
proc append base=d.rat15to17 data=d.rat16; run;
proc append base=d.srat15to17 data=d.rat17; run;

Thanks,

Chloe

[PeterClemmensen · Accepted solution]

A difficult question to answer without knowing the data. 

Are the variable lengths equal? Are any of the data sets compressed?

[CC13]

Thank you for the answers!

The variable lengths are different and I checked I didn't compress the data in the new files which caused the size difference.