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CHAPTER 27 • THE MANY MYSQL CLIENTSwww.it-ebooks.infoVarying degrees of checks are also available, each of which requires additional time but morethoroughly reviews the table for errors. Although the default is simply check (--check), there also exists amedium check (--medium-check) and an extended check (--extend-check). Only use the extended checkfor the most severe cases; the medium check will catch the overwhelming majority of errors andconsume considerably less time. You can review extended information for each of these checks bysupplying the --information (-i) option, which offers various table-specific statistics.If problems are identified with the table, you’ll be notified accordingly. If an error is found, you canask myisamchk to attempt to repair it by supplying the --recover (-r) option:%>myisamchk -r /usr/local/mysql/data/corporate/staff.MYINote that what is presented here is just a smattering of the options available to this utility. Definitelyconsult the manual before using myisamchk to check or repair tables. Also, you should only run myisamchkwhen the MySQL server daemon is not running. If you don’t have the luxury of taking your databaseserver offline, take a look at the next utility, mysqlcheck.mysqlcheckThe mysqlcheck utility offers users the means for checking and, if necessary, repairing corrupted tableswhile the MySQL server daemon is running. It can be invoked in any of the three following ways:%>mysqlcheck [options] database [tables]%>mysqlcheck [options] --databases database1 [database2...]%>mysqlcheck [options] --all-databasesIn addition to the typical user credentials and concerned databases and tables, you can specifywhether you want to analyze (-a), repair (-r), or optimize (-o) by passing in the appropriate parameter.So, for example, suppose the staff table, located in the database corporate, became corrupted due tosudden hard-drive failure. You could repair it by executing:%>mysqlcheck -r corporate staffLike myisamchk, mysqlcheck is capable of finding and repairing the overwhelming majority of errors.In addition, it offers a wide-ranging array of features. Therefore, before you use it to resolve any missioncriticalproblems, take some time to consult the MySQL manual to ensure that you’re using the mosteffective set of options.Client OptionsThis section highlights several of the options shared by many of MySQL’s clients, mysql and mysqladminincluded. The options are divided into two categories: connection options and general options. Beforemoving on to a breakdown of the options falling under these two categories, take a moment to review afew simple rules that you should keep in mind when using these options:• Options can be passed to clients in three ways: via the command line, environmentvariables, or configuration files. If you plan on using a particular option repeatedly, thepreferred way to set it is through a configuration file. MySQL’s configuration files werefirst introduced in Chapter 26.520