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How is string type data stored in the PI Data Archive?

Question asked by DavidMFairchild on Jul 20, 2020

As a PI administrator for 20 years for four different companies I have always counselled people against using string type for PI Tags.  It would very rarely be the best alternative.  Now I have come across a location that uses PI to store log entries, just random text  from 10 to 150 characters describing thing going on at the site.   Log entries.  I'm looking to moving them to a SQL based logging system, but I'm looking for some valid arguments to explain to the site why it's a bad idea to use string type in a PI Data Archive.

 

I've looked through the System Management Guide and the Archive Reference Guide and don't see much on this topic.  So can anyone tell me:

 

1.  Where does the Data Archive store string data?

 

2.  How does PI locate the values to return them when requested?

 

3.  How efficient is storing data in strings?

 

 

A good reference that discusses these topics would be fine.

 

Thanks

 

Daivd Fairchild

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