(mysql.info.gz) MyISAM table close

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(mysql.info.gz) Corrupted MyISAM tables

(mysql.info.gz) MyISAM table problems

 
 14.1.4.2 Problems from Tables Not Being Closed Properly
 .......................................................
 
 Each `MyISAM' index (`.MYI') file has a counter in the header that can
 be used to check whether a table has been closed properly.  If you get
 the following warning from `CHECK TABLE' or `myisamchk', it means that
 this counter has gone out of sync:
 
      clients are using or haven't closed the table properly
 
 This warning doesn't necessarily mean that the table is corrupted, but
 you should at least check the table to verify that it's okay.
 
 The counter works as follows:
 
    * The first time a table is updated in MySQL, a counter in the
      header of the index files is incremented.
 
    * The counter is not changed during further updates.
 
    * When the last instance of a table is closed (because of a `FLUSH
      TABLES' operation or because there isn't room in the table cache),
      the counter is decremented if the table has been updated at any
      point.
 
    * When you repair the table or check the table and it is found to be
      okay, the counter is reset to zero.
 
    * To avoid problems with interaction with other processes that might
      check the table, the counter is not decremented on close if it was
      zero.
 
 
 In other words, the counter can go out of sync only under these
 conditions:
 
    * The `MyISAM' tables are copied without a preceding `LOCK TABLES'
      and `FLUSH TABLES'.
 
    * MySQL has crashed between an update and the final close.  (Note
      that the table may still be okay, because MySQL always issues
      writes for everything between each statement.)
 
    * A table was modified by `myisamchk --recover' or `myisamchk
      --update-state' at the same time that it was in use by `mysqld'.
 
    * Many `mysqld' servers are using the table and one server performed
      a `REPAIR TABLE' or `CHECK TABLE' on the table while it was in use
      by another server.  In this setup, it is safe to use `CHECK TABLE',
      although you might get the warning from other servers. However,
      `REPAIR TABLE' should be avoided because when one server replaces
      the data file with a new one, this is not signaled to the other
      servers.
 
      In general, it is a bad idea to share a data directory among
      multiple servers.  See  Multiple servers for additional
      discussion.
 
 

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(mysql.info.gz) Corrupted MyISAM tables

(mysql.info.gz) MyISAM table problems