topic Re: Size of the zipped data set is different from its size before it was zipped in SAS Data Management

Size of the zipped data set is different from its size before it was zipped

iSAS — Mon, 25 Jun 2018 04:48:40 GMT

We zipped a dataset using:

- call system("gzip path/data.sas7bdat")

However, when we unzipped it using:

- call system("gzip -d path/data.sas7bdat")

We noticed that its size was different from before it was zipped. Does this mean that something changed in the data set? We compared it from its back up data set using proc compare though but there is no discrepancy. However, their file sizes are different. May we know the reason behind this?

Re: Size of the zipped data set is different from its size before it was zipped

Kurt_Bremser — Mon, 25 Jun 2018 07:48:16 GMT

@iSAS wrote:

We zipped a dataset using:

- call system("gzip path/data.sas7bdat")

However, when we unzipped it using:

- call system("gzip -d path/data.sas7bdat")

We noticed that its size was different from before it was zipped. Does this mean that something changed in the data set? We compared it from its back up data set using proc compare though but there is no discrepancy. However, their file sizes are different. May we know the reason behind this?

That wouldn't work. gzip creates

path/data.sas7bdat.gz

while

gzip -d path/data.sas7bdat

will find that the sas7bdat is not a gzipped file and would fail. Since the gzip removes the source file, there must be some process that recreated the sas7bdat. So I suggest you do a

mv path/data.sas7bdat path/data_new.sas7bdat
gzip -d path/data.sas7bdat.gz

and then do a visual compare of the size and the timestamps of data_new.sas7bdat and data.sas7bdat, as gzip preserves those during the whole process.

I've never had a change of physical filesize from gzip / gzip -d.

Re: Size of the zipped data set is different from its size before it was zipped

iSAS — Fri, 29 Jun 2018 07:01:34 GMT

My mistake, I mixed it up. We encountered this issue on on cport/cimport and not on gzip