CEDA Limitations

CEDA is not the preferred strategy for network file access in all situations. CEDA has the following limitations:

• CEDA features are implemented for SAS 9 or 8 data sets, PROC SQL views, SAS/ ACCESS views for Oracle and SYBASE, and MDDBs. CEDA does not support SAS 9 or 8 stored programs or catalogs, nor does it support any SAS 6 or earlier files. The type of access that CEDA has to a SAS file depends on the engine used and the type of file access requested (read, write, update). For more information about file access limitations, see the topic in SAS Language Reference: Concepts that discusses when CEDA is supported.

• CEDA does not support update processing for any SAS files.

• CEDA does not support subsetting by means of an index.

• CEDA is available only for operating environments that use directory-based file structures. Under OS/390, CEDA is available only for SAS data sets that reside in a UNIX System Services Directory. Bound libraries that are traditionally used on the OS/390 operating environment do not implement CEDA.

• Network resources are consumed each time CEDA translates a SAS file.

If you have performance problems, analyze file access patterns to determine whether the data set is located on the correct machine. For example, if the SAS data set is represented in UNIX data format and most of the read operations originate from Windows machines, you might consider moving the data set to a Windows machine and changing the data set's UNIX file format to Windows format. Windows access to a network-mounted file in Windows format would not require CEDA. However, CEDA would be used to translate between the native Windows format of the SAS file being accessed and the accessing machines other than Windows (such as UNIX, z/OS, and OpenVMS).

For complete details about the types of data that CEDA supports and restrictions on using CEDA, see "Processing Data Using Cross-Environment Data Access" in SAS Language Reference: Concepts .

To overcome limited access and network impact limitations, you can change the format of the SAS file from its native format to a foreign format and transfer the SAS file to a different machine. For example, if you determine that a SAS file that was created in HP_UX representation is primarily accessed by PCs, then you might change the format of the SAS file to Windows format and transfer it to a Windows machine. Changing the file's format will improve performance and allow write and update access.