Trouble with appending

[issac ann]

Hi, I am appending two files with observations of 2.94million in each. The command I have used is

append using all_observationsA all_observationsB

However after appending the result file has a count of 8.84million observations in total. The data is getting duplicated somewhere, but I do not understand why. Please can you advise. Thanks.

[Rich Goldstein]

you apparently missed the following part of the help file: "append appends Stata-format datasets stored on disk to the end of the dataset in memory." and note that 2.94*3 is 8.82 which is clearly within rounding error of your 8.84 - so, have one data set in memory and then append only the other data set