Understanding CAS: 6 Key CAS Data Concepts

[#1]

Are you new to CAS? Or, maybe you just want to understand it better? Here are 6 key data concepts:

1. Loaded Tables: CAS is not only an analytic and data transformation engine. It is also a data server. With a few exceptions, you need to load your data into CAS for CAS to analyze or process it.

   

2. DataSource Tables: CAS utilizes a two storage area paradigm. Actual CAS tables are temporary, "in-memory" data structures. To provide data persistence, CAS tables are "backed" by a redundant data store. This data store, called the "DataSource" in the CASLib statement, can be one of many formats including files on disk (e.g. SASHDAT, SAS7BDAT, CSV, etc.) as well as 3rd party data providers like Oracle, SQL Server, and Hadoop. When tables exist in the DataSource but have not been loaded in CAS, they are called "unloaded."

   

3. Session Scoped Tables: CAS is a session-based server. To utilize CAS, you must first create a CAS session and all the work you do occurs within that session. By default, any tables you create are session-scoped tables, meaning that they are only available to your session. Other CAS users and applications will not see your CAS tables. They are "loaded" CAS tables but are only visible within the session that created them. Session scoped CAS tables are useful for data processing, ad-hoc analysis, and any other use case that only requires a single CAS session access the table.

   

4. Global Scoped Tables: While CAS creates session-scoped tables by default, you can also promote CAS tables to global scope. Global scoped CAS tables can be seen and utilized by any CAS session (assuming appropriate authorization) Global scoped CAS tables are useful for end-user applications like Visual Analytics and Visual Statistics that requires the table be available to multiple users.

   

5. Server Side Loading: CAS performs various functions including predictive analytics, text analytics, and data transformation. It can also load data to itself. When CAS accesses external data and loads that data to itself, it is called "Server Side Loading." The server, CAS, loads CAS. Server side loading can take a few different forms including:
   • Serial loading
   • Parallel Loading
   • Multi-Node Data Transfer
   • Cross Loading
   In each case, CAS accesses data in some defined CAS Data Source and loads the data into CAS.

   

6. Client Side Loading: When CAS is loaded by something other than itself, we call that "client side loading." In client side loading, some external application -- either base SAS, Python, LUA, REST, Java, or R -- starts a CAS session and uses CAS actions to load data from the client into CAS. As the diagram below shows, the data is loaded only into CAS ("in-memory") and is not loaded to the defined data source. If you want the data loaded to the defined data source, you'll have to issue a SAVE CAS action.