Caution!

• Experimentation is great, however some use of the database can cause problems.

  • Try to only join or search on an indexed column
    • Tables can be tens of gigabytes, so a full table scan will bring the system to its knees
  • Use MySQL's “explain” syntax
    • It will tell you about how the query will be performed without actually executing.
    • Make sure it has a index referenced in the “KEY” column

Notes: