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  1. #1
    Join Date
    Oct 2011

    Unanswered: Open table in MySQL

    Hi All,
    I'm pretty much new in MySQL so hope you guys can guide me. I would like to know what will be the ideal value to be set for open table and open files in mysql. I believe the default value would be 470 for open tables. What criteria do i need to look upon before modifying this value? Basically, the normal open table range in MySQL server would be in the range of 150-200. But last week we receive a high amount of open table in the range of 450- 480. What would be the cause/reason that trigger this scenario. There is no lock or any error in mysql log file. Anyone encounter this scenario what is root cause for the trigger and how can i avoid it.

  2. #2
    Join Date
    Sep 2009
    San Sebastian, Spain
    There are several criteria for determining the table_cache parameter. These include the number of processes, the number of tables opened at any one time for a query and the application and how it has been developed.

    There is no one size fits all, you should have a look at the number of open tables versus the number of opened tables and determine whether the number of opened tables is growing very quickly.

    Someone also posted earlier in the week that there was little evidence that increasing the table_cache parameter that this would actually give any (and actually indicates a worsening of) performance. table_cache negative scalability - MySQL Performance Blog
    Ronan Cashell
    Certified Oracle DBA/Certified MySQL Expert (DBA & Cluster DBA)
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