topic DATAn naming scheme and rollover in SAS Programming

DATAn naming scheme and rollover

gabonzo — Wed, 17 Mar 2021 20:35:17 GMT

I use the _DATA_ trick a lot, especially for temporary datasets that I create inside macros and then delete when the macro has been executed.

I have found a problem with that though: it seems to me that the number 'n' in the DATAn naming scheme rolls over at some point, and n starts over from 1.

This causes a lot of problems, and my programs stop working.

I don't see in the documentation when the rollover is, does anybody know:

What the maximum allowed number for DATAn is
If it is possible to extend it

Thanks

Re: DATAn naming scheme and rollover

ChrisHemedinger — Wed, 17 Mar 2021 20:49:46 GMT

I don't have an answer for your exact question, but I do have some advice from my experience. When I'm creating a series of temp/scratch data sets that I'm going to turn around and delete at the end of a process, I like to isolate them to their own folder (outside of WORK library). That gives me more options for deleting the whole shebang without worrying about conflicts.

I documented this in How to delete SAS data sets. Specifically the trick I use is this:

/* create a subfolder in WORK for my data */ options dlcreatedir; libname scratch "%sysfunc(getoption(WORK))/scratch"; /* just adding some data for example purpose */ data scratch.a1 scratch.a2 scratch.a3; set sashelp.class; run; /* more operations with scratch data */ /* now clear it when ready */ proc datasets lib=scratch kill nolist; quit;

Re: DATAn naming scheme and rollover

gabonzo — Wed, 17 Mar 2021 21:01:37 GMT

I like your idea, but it would be tricky to use it to solve my problem.

I don't create that many datasets per macro (perhaps three at most), but I have many macros, and in the current task I am doing a statistic simulation where I have to run the same set of macros over and over again for tens of thousands of times.

One way I could use your trick is to create a subfolder for each macro, but I am concerned the overhead will slow down an already slow program. Moreover, isn't PROC DATASETS supposed to be a bit of a resource hog?

Thanks anyway

Re: DATAn naming scheme and rollover

Reeza — Wed, 17 Mar 2021 21:09:23 GMT

Not a solution but similar to @ChrisHemedinger I use a common prefix, typically _dataSetName for all my temp tables and then drop them at once at the end using PROC DATASETS and the shortcut colon.

proc datasets lib=work;
delete _: ;
run;quit;

Here is a reference that illustrates how to refer to variables and datasets in a short cut list:
https://blogs.sas.com/content/iml/2018/05/29/6-easy-ways-to-specify-a-list-of-variables-in-sas.html

@gabonzo wrote:

I use the _DATA_ trick a lot, especially for temporary datasets that I create inside macros and then delete when the macro has been executed.

I have found a problem with that though: it seems to me that the number 'n' in the DATAn naming scheme rolls over at some point, and n starts over from 1.

This causes a lot of problems, and my programs stop working.

I don't see in the documentation when the rollover is, does anybody know:

What the maximum allowed number for DATAn is

If it is possible to extend it

Thanks

Re: DATAn naming scheme and rollover

gabonzo — Wed, 17 Mar 2021 21:17:45 GMT

Ok, it seems a consensus is forming. Perhaps I will go with this solution.

Re: DATAn naming scheme and rollover

ChrisHemedinger — Wed, 17 Mar 2021 21:22:55 GMT

If you don't like PROC DATASETS (it does have some overhead), then PROC DELETE is quick and light. You can delete a range, but not a "wildcard" list.

proc delete library=work data=DATA1-DATA5; run;