How to Join on Multiple Keys in a CAS View

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The join functionality in a CAS View has been extended. You can now join tables on multiple keys since the SAS Viya 2020.1.3 stable cadence. Therefore, the changes are included in the 2021.1 long term support.

If you are not familiar with the star schemas in CAS, I recommend reviewing the following posts:

• Query Performance? Use a CAS Star Schema in Viya 3.5
• Automatic Data Loading with a CAS Data Source Star Schema
• CAS Views vs. Data Views

 

Before SAS Viya 2020.1.3

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After SAS Viya 2020.1.3

Code

You can now specify multiple join keys. For example, the customer code and the record source:

{keys={'m_customer_code = c_customer_code', 'm_record_source = c_record_source'}

To create a CAS View (the star schema in the second diagram), you could write:

cas mySession sessopts=(caslib="casuser" timeout=1800 locale="en_US" 
	metrics="true" dqLocale="(ENUSA)");
caslib _all_ assign;
* Multi-key join FACT + DIM 2 keys + DIM one key;
proc casutil;
droptable casdata="mail_view_multi" incaslib="casuser" quiet;
quit;
proc cas;
table.view / promote=true name='mail_view_multi'
tables={
{name='mailorder_mkey', varlist={'qty'}, as='m'},
{keys={'m_customer_code = c_customer_code', 'm_record_source = c_record_source'},
name='customers_mkey',
varList={'addr1','addr2','city',
'region','state','zip'}, as='c'},
{keys={'m_pcode = p_pcode'},
name='products_rep',  varlist={'price', 'cost', 'descrip', 'type'},
computedVars={{name="price_cost_ratio"}}, 
computedVarsProgram="price_cost_ratio = price/cost;", as='p'},
{keys={'m_catcode = cat_catcode'},
name='catcode_rep', varlist={'catalog'}, as='cat'}
};
quit;
cas mySession terminate;

Note how the price cost ratio is defined as a calculation within the view.

 

Pre-requisites

Facts and dimensions tables loaded in CAS.

 

Acknowledgements

Special thanks to Gordon Keener in SAS R&D for his time, efforts, and sharing information on this topic.

 

References

I would recommend the following resources:

• Query Performance? Use a CAS Star Schema in Viya 3.5
• Automatic Data Loading with a CAS Data Source Star Schema
• CAS Views vs. Data Views

Thank you for your time reading this post. Please share your experience with the CAS Star Schemas and help others.

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