@Weezy_bks wrote: log with NODUPRECS option : 30 options obs=max; 31 options compress=yes; 32 33 34 proc sort data = test_1 NODUPRECS out = data_in dupout = data_out; 35 by _ALL_; 36 run; NOTE: There were 6 observations read from the data set WORK.TEST_1. NOTE: 0 duplicate observations were deleted. NOTE: The data set WORK.DATA_IN has 6 observations and 21 variables. NOTE: Compressing data set WORK.DATA_IN increased size by 100.00 percent. Compressed is 2 pages; un-compressed would require 1 pages. NOTE: The data set WORK.DATA_OUT has 0 observations and 21 variables. NOTE: PROCEDURE SORT used (Total process time): real time 0.01 seconds cpu time 0.00 seconds by replacing NODUPRECS by NODUPKEY : options obs=max; 31 options compress=yes; 32 33 34 proc sort data = test_1 nodupkey out = data_in dupout = data_out; 35 by _ALL_; 36 run; NOTE: There were 6 observations read from the data set WORK.TEST_1. NOTE: 0 observations with duplicate key values were deleted. NOTE: The data set WORK.DATA_IN has 6 observations and 21 variables. NOTE: Compressing data set WORK.DATA_IN increased size by 100.00 percent. Compressed is 2 pages; un-compressed would require 1 pages. NOTE: The data set WORK.DATA_OUT has 0 observations and 21 variables. NOTE: PROCEDURE SORT used (Total process time): real time 0.01 seconds cpu time 0.00 seconds The case is very clear: there are NO duplicates when all 21 variables are considered. ... View more