Cross-Environment Data Access (CEDA)

CEDA Limitations

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

CEDA features are implemented for SAS 9 or SAS 8 data sets, PROC SQL views, SAS/ACCESS views for Oracle and Sybase, and MDDBs. CEDA does not support SAS 9 or SAS 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 When Is CEDA Supported? .
CEDA does not support update processing for any SAS files.
CEDA does not support subsetting by means of an index.
CEDA can read audit trails but it cannot update them.
The processing of integrity constraints is not supported.
CEDA is available only for operating environments that use directory-based file structures. Under z/OS, CEDA is available only for SAS data sets that reside in a UNIX System Services Directory. Bound libraries that are traditionally used on the z/OS operating environment do not implement CEDA.
Network resources are consumed each time CEDA translates a SAS file.
Transcoding could result in character data loss when encodings are incompatible. For details about encoding and transcoding, see SAS National Language Support (NLS): Reference Guide.
If a file that is in a foreign format is damaged, it cannot be repaired because CEDA does not support update processing, which is the strategy that you use to repair a damaged data set. To repair the file, you must move it back to the source environment. For details about repairing a damaged data set, see the REPAIR statement in the DATASETS procedure in the Base SAS Procedures Guide.
Numeric variables have a minimum length of either 2 or 3 bytes, depending on the operating environment. In an operating environment that supports a minimum of 3 bytes (such as Windows or UNIX), CEDA cannot process a numeric variable that was created with a length of 2 bytes (for example, in z/OS). If you encounter this restriction, use the XPORT engine or the CPORT and CIMPORT procedures instead of CEDA.
Loss of precision can occur in numeric variables when you move data between operating environments. If a numeric variable is defined with a short length, you can try increasing the length of the variable. Full-size numeric variables are less likely than short numeric variables to encounter a loss of precision with CEDA. For more information, see the topic about numeric precision in SAS Language Reference: Concepts.

If you have performance problems, analyze file access patterns to determine whether the data set is located on the correct computer. For example, if the SAS data set is represented in UNIX data format, but most of the read operations originate from Windows computers, you might consider moving the data set to a Windows computer 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. Changing the file's format would improve performance and allow write and update access. However, CEDA would be used to translate between the native Windows format of the SAS file being accessed and the accessing computers 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.

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