<p>This article describes how to modify major parameters in the RDS console.</p> <p><span style="font-size:18px"><strong>Overview</strong></span></p> <p>RDS MySQL service features function of parameter management. You can set advanced parameters that are relevant to MySQL engine to optimize performance.</p> <p><span style="font-size:18px"><strong>Parameter Description</strong></span></p> <table border="1" cellpadding="0" cellspacing="0" style="width:786px"> <tbody> <tr> <td style="background-color:#ededed; vertical-align:top; width:179px"> <p><strong>Parameter</strong></p> </td> <td style="background-color:#ededed; vertical-align:top; width:71px"> <p><strong>Default value</strong></p> </td> <td style="background-color:#ededed; vertical-align:top; width:74px"> <p><strong>Whether need to reboot an instance</strong></p> </td> <td style="background-color:#ededed; vertical-align:top; width:451px"> <p><strong>Description</strong></p> </td> </tr> <tr> <td style="vertical-align:top; width:179px"> <p>back_log</p> </td> <td style="vertical-align:top; width:71px"> <p>3000</p> </td> <td style="vertical-align:top; width:74px"> <p>Yes</p> </td> <td style="vertical-align:top; width:451px"> <p>A new thread will be created when MySQL processes a connection request. When the primary thread is creating a new thread, MySQL will not accept new connection request if there are large number of requests for short connections to database and quantity of waiting connections exceeds the value of back_log. If you would deal with a large amount of short connections with MySQL, you need to increase the value of the parameter.</p> </td> </tr> <tr> <td style="vertical-align:top; width:179px"> <p>innodb_autoinc_lock_mode</p> </td> <td style="vertical-align:top; width:71px"> <p>1</p> </td> <td style="vertical-align:top; width:74px"> <p>Yes</p> </td> <td style="vertical-align:top; width:451px"> <p>Auto increment lock mode:</p> <p>&bull;&nbsp; 0: Traditional mode</p> <p>&bull;&nbsp; 1: Incremental mode</p> <p>&bull;&nbsp; 2: Lock-free</p> <p>The default value of RDS MySQL is 1. It represents that InnoDB uses lightweight mutex to replace the original table-level lock with obtained auto increment lock.</p> </td> </tr> <tr> <td style="vertical-align:top; width:179px"> <p>query_cache_size</p> </td> <td style="vertical-align:top; width:71px"> <p>3145728</p> </td> <td style="vertical-align:top; width:74px"> <p>No</p> </td> <td style="vertical-align:top; width:451px"> <p>Query the maximum buffer length.</p> <p>The query of maximum buffer length is not enabled by default. The maximum buffer length is 0.</p> <p>The value should be multiples of 1024, otherwise it will be closest floor value.</p> </td> </tr> <tr> <td style="vertical-align:top; width:179px"> <p>net_write_timeout</p> </td> <td style="vertical-align:top; width:71px"> <p>60</p> </td> <td style="vertical-align:top; width:74px"> <p>No</p> </td> <td style="vertical-align:top; width:451px"> <p>Timeout for sending a block to a client.</p> </td> </tr> <tr> <td style="vertical-align:top; width:179px"> <p>tmp_table_size</p> </td> <td style="vertical-align:top; width:71px"> <p>33554432</p> </td> <td style="vertical-align:top; width:74px"> <p>No</p> </td> <td style="vertical-align:top; width:451px"> <p>The maximum value of internal temporary table created in memory.</p> <p>If size of the memory temporary table exceeds limit, MySQL will automatically transform it to a disk-based MyISAM table.</p> </td> </tr> </tbody> </table>