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Query Optimization - Coggle Diagram

- - - - without All -> adding the distinct option to the temporary table
  - - - it can use a temporary table to group
      - it can use a filesort to group
- - - - Fetching all columns from a multitable join
      - Fetching all columns
        
        Some DBAs even ban SELECT*
      - Fetching more rows than needed
        
        to add a LIMIT clause to the query
      - Fetching the same data repeatedly
  - - - whether your application is retrieving more data than you need
      - whether the MySQL server is analyzing more rows than it needs.
  - - - Service time - time to process the query
      - Queue time - time of waiting (f.e.a row lock, I/O operation to complete)
      - the following factors also have influence
        
        high concurrency
        
        hardware
        
        storage engine locks
    - - Ideally, the number of rows examined is the same as the number returned