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| From: | Hartmut Holzgraefe | Date: | March 2 2010 9:49am |
| Subject: | Re: How to implement genuine HA without losing any data if one SQL node of mysql cluster out of service? | ||
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Hi Peter, > Are there some other third party softwares that can be used to implement > load-balance and fail-over without updating my application? your application has to be able to handle temporary transaction failures anyway. Even without failovers there is always a chance of temporary transaction failures, e.g. due to timeouts, deadlock detection, or other temporary failures. E.g. with MySQL Cluster you may also get temporary transaction failures if a data node taking part in a transaction dies, in that case you'll receive a temporary transaction failure error code and need to redo the transaction on the application level, too. The database guarantee towards the application is that once a COMMIT has succeeded without error the data written by the committed transaction won't be lost (the 'D' part of 'ACID'). Up to that point it is the duty of the application to deal with transaction failures though, and no third party solution could know your applications logic and decide how to redo the transaction safely automatically on behalf of your application. -- Hartmut Holzgraefe, MySQL Regional Support Manager, EMEA Sun Microsystems GmbH, Sonnenallee 1, D-85551 Kirchheim-Heimstetten Amtsgericht München: HRB 161028 Geschäftsführer: Thomas Schröder, Wolfgang Engels Vorsitzender des Aufsichtsrates: Martin Häring