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• Finding and Fixing Slow SQL Queries

  Finding and Fixing Slow SQL Queries

  Content Type
  Video

  Duration
  9m

  Level
  Intermediate

  Learn how to identify and improve slow SQL queries in InterSystems® products. See how to use the SQL query plan to find query performance issues, and how to implement changes to improve efficiency.

  Basic experience using SQL in InterSystems IRIS® data platform is assumed. If needed, try Running Fast Queries with SQL in InterSystems IRIS (exercise, 10m).
• Code Used in This Video

  Code Used in This Video

  Reference	Timestamp	Code
  Query that tallies the number of 'SELL' transactions performed for each stock	2:04	SELECT Symbol, DateTransaction, count(*) as TransactionNumber FROM Data.StockData WHERE TransactionType = 'SELL' AND DateTransaction = '04/23/2018' GROUP BY Symbol
  Create index on DateTransaction field	6:50	CREATE BITMAP INDEX DateIdx ON TABLE Data.StockData(DateTransaction)
  Use the %PARALLEL hint to suggest parallelization of a query	8:26	SELECT Symbol, DateTransaction, count(*) as TransactionNumber FROM %PARALLEL Data.StockData WHERE TransactionType = 'SELL' AND DateTransaction = '04/23/2018' GROUP BY Symbol
• What's Next?

  What's Next?
  • Get hands-on practice optimizing SQL Queries (exercise, 15m).
  • Read more about interpreting query plans (documentation, 25m).
    
  • Watch another demonstration that shows how to optimize a slow query (video, 40m).
  • Get a deeper understanding of the SQL query optimizer (video, 35m).