15. Video + Quiz: Performance Tuning 1

How You Can and Can't Control Performance

More on Performance Tuning

One way to make a query run faster is to reduce the number of calculations that need to be performed. Some of the high-level things that will affect the number of calculations a given query will make include:

  • Table size
  • Joins
  • Aggregations

Query runtime is also dependent on some things that you can’t really control related to the database itself:

  • Other users running queries concurrently on the database
  • Database software and optimization (e.g., Postgres is optimized differently than Redshift)

Performance Tuning 1

Performance Tuning with LIMIT

Select all of the following statements that are true about tuning performance with LIMIT.
SOLUTION:
  • If you have time series data, limiting to a small time window can make your queries run more quickly.
  • Testing your queries on a subset of data, finalizing your query, then removing the subset limitation is a sound strategy.
  • When working with subqueries, limiting the amount of data you’re working with in the place where it will be executed first will have the maximum impact on query run time.

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