For more information on this, have a look here:
SAS® 9.4 and SAS® Viya® 3.4 Programming Documentation Introduction to SAS Platform Graphing
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Overview of Using Data That Is Processed In CAS
When data resides in the SAS Cloud Analytic Services (CAS) environment, the data can be accessed by the ODS Graphics procedures through the CAS LIBNAME engine. The CAS LIBNAME engine enables the procedures to access and download CAS tables to the SAS client, such as SAS Studio. For more information about creating a CAS libref, see SAS Cloud Analytic Services: User’s Guide.
For this release of SAS Viya, the analytics for the ODS Graphics procedures are performed in the SAS client instead of the CAS environment. Therefore, for large data situations, it is recommended that you summarize or reduce the data before attempting to graph it. For example, in CAS procedure you can use the AGGREGATE action to summarize your large data to another CAS table, Then, you can reference the summarized CAS data from the SGPLOT or SGPANEL procedures to create a bar chart using the HBARPARM or VBARPARM statements.
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