Comments on: Creating an Intermediate Replication Layer http://blog.onefreevoice.com/2008/07/15/creating_intermediate_slaves/ A Blog About Databases and Stuff Sun, 05 Apr 2009 04:01:31 +0000 http://wordpress.com/ hourly 1 By: How MySQL Sandbox Solves All My Problems « OneFreeVoice http://blog.onefreevoice.com/2008/07/15/creating_intermediate_slaves/#comment-479 How MySQL Sandbox Solves All My Problems « OneFreeVoice Sun, 05 Apr 2009 04:01:31 +0000 http://blog.onefreevoice.com/?p=103#comment-479 [...] getting complicated? To you have two many slaves running off a single master and need to introduce a new layer. Mysql_sandbox comes with several prepared schemes out of the box, including standard, circular, [...] [...] getting complicated? To you have two many slaves running off a single master and need to introduce a new layer. Mysql_sandbox comes with several prepared schemes out of the box, including standard, circular, [...]

]]> By: Gregory Haase http://blog.onefreevoice.com/2008/07/15/creating_intermediate_slaves/#comment-396 Gregory Haase Mon, 28 Jul 2008 15:10:04 +0000 http://blog.onefreevoice.com/?p=103#comment-396 I made one final edit to this procedure. The <code>START SLAVE UNTIL</code> directive only causes the slave SQL thread to stop at the given bin-log and position. At this point, the slave IO thread is still running. The original script had a <code>RESET SLAVE</code> call immediately after <code>MASTER_POS_WAIT</code>. This resulted in the error: <pre lang="sql">ERROR 1198 (HY000) at line 6: This operation cannot be performed with a running slave; run STOP SLAVE first</pre> Inserting <code>STOP SLAVE</code> before <code>RESET SLAVE</code> resolves the issue. I made one final edit to this procedure. The START SLAVE UNTIL directive only causes the slave SQL thread to stop at the given bin-log and position. At this point, the slave IO thread is still running. The original script had a RESET SLAVE call immediately after MASTER_POS_WAIT. This resulted in the error:

ERROR 1198 (HY000) at line 6: This operation cannot be performed with a running slave; run STOP SLAVE first

Inserting STOP SLAVE before RESET SLAVE resolves the issue.

]]> By: Gregory Haase http://blog.onefreevoice.com/2008/07/15/creating_intermediate_slaves/#comment-389 Gregory Haase Tue, 15 Jul 2008 19:46:08 +0000 http://blog.onefreevoice.com/?p=103#comment-389 Thank you Mats for catching that one. I've edited the original thread to include MASTER_POS_WAIT as you suggested. Thank you Mats for catching that one. I’ve edited the original thread to include MASTER_POS_WAIT as you suggested.

]]> By: Mats Kindahl http://blog.onefreevoice.com/2008/07/15/creating_intermediate_slaves/#comment-388 Mats Kindahl Tue, 15 Jul 2008 19:22:18 +0000 http://blog.onefreevoice.com/?p=103#comment-388 Uhm... as I understand what you are trying to accomplish, there is a problem with following the procedure given. If the instructions are followed by the letter, the intermediate slave will be reset <em>immediately</em> and not when the slave reaches the until-position given in the <code>START SLAVE UNTIL</code>. This is because the <code>START SLAVE UNTIL</code> starts the slave asynchronously, i.e., will return immediately with the slave running. To wait for the slaves to reach the given position before resetting them, it is necessary to add a <code>SELECT MASTER_POS_WAIT('bin-logs.000025', 106)</code> after the <code>START SLAVE UNTIL</code> but before the <code>RESET MASTER</code> and the <code>RESET SLAVE</code> respectively. Uhm… as I understand what you are trying to accomplish, there is a problem with following the procedure given. If the instructions are followed by the letter, the intermediate slave will be reset immediately and not when the slave reaches the until-position given in the START SLAVE UNTIL. This is because the START SLAVE UNTIL starts the slave asynchronously, i.e., will return immediately with the slave running. To wait for the slaves to reach the given position before resetting them, it is necessary to add a SELECT MASTER_POS_WAIT('bin-logs.000025', 106) after the START SLAVE UNTIL but before the RESET MASTER and the RESET SLAVE respectively.

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