What information should be provided when asking how to improve the performance of a query?


As many of the following as possible:

  • Database product, precise version, and edition.
  • Formatted text of the query/procedure/function.
  • Current and desired performance levels.
  • Things you can and cannot change (e.g. can add indexes, cannot change the query).
  • Query plans
    • Ideally the post-execution variety, containing runtime information.
    • Estimated execution plans (if obtaining a post-execution plan is not practical).
    • Anonymized plans are acceptable, but may limit answer quality.
    • A picture of an execution is occasionally enough (but discouraged).
  • A link to a demo that reproduces the core of the problem.
    • Or table, index, and constraint definitions (scripts).
  • Hardware (e.g. memory/CPU/storage) and OS information.
  • The tuning steps followed so far.
  • The tag.

Further reading

  • I'm hoping to keep this answer to a manageable size. Please contribute, but prioritize brevity over comprehensiveness. Feel free to add additional links to the Further reading section at the end. – Paul White says GoFundMonica Aug 27 '18 at 7:35

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