Designer deployment: Why is refresh() executed before drop projection?

MalGMalG Registered User

Vertica community edition: Vertica Analytic Database v7.1.1-0
 

I ran admintools / designer on the VMART sample database.

 

The generated design deployment script starts out with 4 create projection statements for 4 tables in VMART, followed by select refresh(on those 4 tables) operation, select make_ahm_now() operation, then 4 drop projection statements for existing projections for those same 4 tables.
Thus, the design creates new projections for 4 tables, also finds and removes existing projections for those tables.

 

Question: Why is the designer deployment script executing a REFRESH() operation BEFORE the old/obsolete projections are dropped?
 

The Refresh operation is documented as follows:

"REFRESH - Performs a synchronous, optionally-targeted refresh of a specified table's projections."

 

Wouldn’t it make sense to drop and get rid of the obsolete projections before executing a refresh() operation?

 

 What is the reason for executing a refresh() just prior to a drop projection

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