Technology Tales

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WARNING: Engine XPORT does not support SORTEDBY operations. SORTEDBY information cannot be copied.

24th July 2012

When recently creating a transport file using PROC COPY and the XPORT library engine, I found the above message in the log. The code used was similar to the following:

libname tran xport "c:\temp\tran.xpt";

proc copy in=data out=tran;
run;

When I went seeking out the cause on the web, I discovered this SAS Note that dates from before the release of SAS 6.12, putting the issue at more than ten years old. My take on its continuing existence is that we still to use a transport file format that was introduced in SAS 5.x for sake of interoperability, both between SAS versions and across alternatives to the platform.

The SORTEDBY flag in a dataset header holds the keys used to sort the data and it isn’t being copied into the XPORT transport files, hence the warning. To get rid of it, you need to remove the information manually in data step using the SORTEDBY option on the DATA statement or using PROC DATASETS, which avoids rewriting the entire data set.

First up is the data step option:

data test(sortedby=_null_);
set sashelp.class;
run;

Then, there’s PROC DATASETS:

proc datasets;
modify test(sortedby=_null_);
run;
quit;

It might seem counterproductive to exclude the information but it makes no sense to keep what’s being lost anyway. So long as the actual sort order is unchanged, and I believe that the code that that below will not alter it, we can live with its documentation in a specification until transport files created using PROC CPORT are as portable as those from PROC COPY.

Comment:

  • John says:

    Using the new in-built SAS macro LOC2XPT avoids the need to do this and it can create V5, V8 or V9 variants of the XPORT SAS transport file format too. There also is XPT2LOC for extracting datasets from an XPORT transport file.

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