Document created by Jamil on Aug 27, 2019Last modified by Jamil on Aug 27, 2019
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  • What is the purpose of this tuning parameter?

         ArcMaxCollect: Used to limit max. number of compressed events that can be retrieved by a single query from a single client. 


         Archive_MaxQueryExecutionSec: Max time a query can run before timeout. Keeping it too high may cause waiting on large queries and decrease amount of queries which can          be run.

  • What are the defaults?

         ArcMaxCollect: default is 1500000. Value units are in events.

         Archive_MaxQueryExecutionSec: defaul is 260, Value units are in seconds. 

  • Under what conditions do you think you would have to alter the values?

         ArcMaxCollect - I would increase it only if there's a need to run some "big" queries from data amount point of view. But this should be done only to meet some query execution          goal and needs to be set back to lowest/default value back. Lets say if there's need to get all archived data tag values for last several years. 

         Archive_MaxQueryExecutionSec: Again, increasing it will cause the system to wait on "long running queries", like calc ones. 

  • What considerations would you have in resetting this? 

         I would reset these values to default in case if there are constant PI SRV performance issues caused by large\heave queries from some user(s)/scripts, juts to get the          performance back for the all of the other users and find/analyze that queries as the next immediate step. 


And here's the result of Queue files on D:\ drive and PI system stop/start

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