Top 10 most noteworthy MySQL Variables

There are many MySQL variables, some of which are worth noting. The following describes some MySQL variables worth learning for your reference.

1 Threads_connected
Note that the value of this variable cannot show variables like 'threads _ connected ';
Show status like 'threads _ ccted '(The following variable value is also true );
The variable value indicates how many customers are currently connected to the mysql server.
Extended: whether the number of connections is too large. There is a problem in the network! Especially in the case of pconnect :)

2 Created_tmp_disk_tables
Number of temporary tables created on the hard disk
Extended: if this value is relatively large, the create temporary table operation will consume more time during the query.

3 Handler_read_first
The first row of the read Table index.
Extended: if this value changes a lot, you can think that there is a problem with table index creation, and there are many full index scanning operations.

4 Innodb_buffer_pool_wait_free
This variable indicates the number of times MySQL has to wait for memory pages to be flus
Extended: If this variable is high, it suggests that MySQL's memory buffer is incorrectly configured for the amount of writes the server is currently refreshing Ming.
Do not know this :)

5 Key_reads
The number of times the index is read on the file system.
Extended: if this value is too large, you need to consider whether the key cache settings are normal.

6 Max_used_connections
Meaning: the maximum number of connections since the restart
Extended: server load and the number of connections that may need to be adjusted

7 Open_tables
The number of opened tables.
Extended: If the value is very low and the table cache is very large, it is no problem to reduce the table cache settings. If the value is large and close to the value of table cache, we need to increase the talbe cache settings.

8 Select_full_join
Total number of queries
Extended: The value is too large and more indexes need to be created to avoid

9 Slow_queries
The number of slow queries.
Extended: if it is too large, check the slow query log and check whether the SQL statement is properly written.

10 Uptime
Indicates the running time, in seconds.
Extended: This value is useful to analyze server uptime, as well as to generate reports on overall system performance. A consistent low value indicates that the server is being frequently restarted, thereby causing frequent interruptions to client service.

 
 

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