---
layout: article
title: CAS Tables
description: Dealing with CAS (in-memory) Tables in Data Controller
og_image:  /img/SAS-Viya-and-CAS-300x249.png
---

!!! warning
    Work in Progress!

# CAS Tables

CAS Tables require special consideration in Data Controller with regards to the following topics:

 - System Account
 - Loading
 - Unloading
 - Special Variables

## System Account

Despite having a shared SYSUSERID, the SPRE session will (by default) authenticate using the logged-in user credentials.  To get around this, it is necessary to set up the CAS connection in the autoexec - ie, before the user takes over the session.  The code snippet will be:

```sas
%let _CASHOST_ = <your-host>;

%let _CASPORT_ = 5570;

cas dcsession authdomain="<your-domain>" sessopts=(caslib=casuser);
```

The credentials need to be first placed in the viya credentials service as described [here](https://go.documentation.sas.com/doc/en/pgmsascdc/v_073/casref/n0z3r80fjqpobvn1lvegno9gefni.htm#p11ynzjbz96oq1n17rgt2utv6swj).

Another approach can be to use the `AUTHINFO="authentication-file" option, as described [here](https://go.documentation.sas.com/doc/en/pgmsascdc/v_073/casref/n0z3r80fjqpobvn1lvegno9gefni.htm#n174yddgn85756n1v5q4yb881xa0).

Note that since the CAS connection is using a shared account, the CASUSER library is never shown in the DC interface.

## Loading

It can happen that a CAS table is configured in Data Controller but not loaded into memory. In this case, when a user selects the table, it will be automatically loaded.

## Unloading

After an approval, the in-memory version of the CAS Table will be updated.  To apply this to the underlying file on disk, the following code must be executed (eg in a POST APPROVE HOOK):

```sas
proc casutil;
   save casdata="mytable" incaslib="mycaslib"
        casout="mytable" outcaslib="mycaslib"
        replace;
quit;
```

## Special Variables

Processing of data in Data Controller is performed in SPRE with SAS datasets - and as such, it is not possible to process character variables longer than 32k or other CAS specific data types.