In addition to all the variable information we can query, MySQL also keeps track of many useful counters and statistics. These numbers track how often various events occur. The SHOW STATUS command produces a tabular listing of all the statistics and their names.

To confuse matters a bit, MySQL refers to these counters as variables too. In a sense, they are variables, but they’re not variables you can set. They change as the server runs and handles traffic; you simply read them and reset them using the FLUSH STATUS command.

The SHOW STATUS command, though, offers a lot of insight into your server’s perfor mance. It’s covered in much greater depth in Appendix A.   

Show INNODB Status

The SHOW INNODB STATUS status command provides a number of InnoDB-specific sta tistics. As we said earlier, InnoDB is one of MySQL’s storage engines; look for more on storage engines in Chapter 2.

The output of SHOW INNODB STATUS is different from that of SHOW STATUS in that it reads more as a textual report, with section headings and such. There are different sec tions of the report that provide information on semaphores, transaction statistics, buffer information, transaction logs, and so forth.

SHOW INNODB STATUS is covered in greater detail along with SHOW STATUS in Appendix A. Also, note that in a future version of MySQL, this command will be replaced with a more generic SHOW ENGINE STATUS command. 

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