topic Re: Output list of all libraries that use the COMPRESS option? in New SAS User

Output list of all libraries that use the COMPRESS option?

EinarRoed — Thu, 14 Mar 2019 13:44:17 GMT

Is there a way to output a list of all libraries that use the COMPRESS option?

Re: Output list of all libraries that use the COMPRESS option?

Astounding — Thu, 14 Mar 2019 13:53:05 GMT

The COMPRESS option (and the method used) is applied on a data set by data set level. It is not applicable at the library level. That being said, you should be able to extract the information on each data set from dictionary.tables.

Re: Output list of all libraries that use the COMPRESS option?

PeterClemmensen — Thu, 14 Mar 2019 13:57:20 GMT

I don't think the information exists in SAS metadata on library level. The obvious place to look would be the dictionary.libnames table, but no..

Re: Output list of all libraries that use the COMPRESS option?

andreas_lds — Thu, 14 Mar 2019 14:02:35 GMT

Interesting: you can set compress in the libname-statement, but the information is not in sashelp.vlibnam, but in sashelp.vtable (or dictionary.tables).

Re: Output list of all libraries that use the COMPRESS option?

ballardw — Thu, 14 Mar 2019 14:33:56 GMT

@andreas_lds wrote:

Interesting: you can set compress in the libname-statement, but the information is not in sashelp.vlibnam, but in sashelp.vtable (or dictionary.tables).

Possibly because some data sets don't gain anything when "compressed"? You can get this message when SAS determines that attempting to compress would result in a larger file size:

NOTE: Compression was disabled for data set WORK.ONE because compression 
      overhead would increase the size of the data set.

because the compress option, which can be a System option as well as library or dataset, adds a block of data to each observation related to the compression.

Re: Output list of all libraries that use the COMPRESS option?

Astounding — Thu, 14 Mar 2019 14:38:31 GMT

Remember, the same folder can switch options from one program to the next. In one program, the libname-level option could be yes, and in another in could be no. The individual data sets within a library can use different compression options, regardless of what appears in one particular program.

Re: Output list of all libraries that use the COMPRESS option?

Tom — Thu, 14 Mar 2019 21:26:22 GMT

@andreas_lds wrote:

Interesting: you can set compress in the libname-statement, but the information is not in sashelp.vlibnam, but in sashelp.vtable (or dictionary.tables).

There are a lot of LIBNAME settings that cannot be determined from that metadata.

Note that the default setting for compress that is defined for the libref can be overridden at the dataset level via the dataset option COMPRESS=. Also SAS will sometimes override the users setting completely. If you try to add compression to a very skinny dataset then SAS will turn it off since it will just make the dataset larger.

So even if you could find the libref level default setitng it wouldn't really tell you anything other than what default compression MIGHT be applied to the next dataset created using that libref.