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MySQL Conference Liveblogging: MySQL Performance Under A Microscope: The Tobias And Jay Show (Wednesday 2:00PM)
  • Jay Pipes, Tobias Asplund
  • Finding out the number of rows that would have been returned (MyISAM and InnoDB)
    • SQL_CALC_FOUND_ROWS and FOUND_ROWS()
    • COUNT(*)
    • MEMORY table
    • if query cache is on, then it makes no difference
    • if it's off
      • Memory MyISAM is fastest
      • FOUND_ROWS() is slightly slower than count(*)
    • more in the slides that I'll add later
  • quite a lot of humor, these guys are fun
  • query union vs index_merge union
    • SELECT … WHERE a UNION SELECT … WHERE b
      vs
      SELECT … WHERE a AND b
    • index_merge wins
  • composite index vs index merge
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