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MySQL Conference Liveblogging: MySQL Performance Under A Microscope: The Tobias And Jay Show (Wednesday 2:00PM)


Posted by Artem Russakovskii on April 16th, 2008 in Databases

  • 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
    • composite index is faster
    • of course, multiple indexes are more flexible than composite index
  • sort union vs composite index
    • …
  • unix time (int unsigned) vs datetime