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From:Dr. Frank Ullrich Date:November 16 2006 8:07am
Subject:Re: SELECT /*!40001 SQL_NO_CACHE */ * FROM `ROUTEDATA` message
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Logg, Connie A. wrote:
> I am running mysql version 5.0.24 and am seeing this error when running mysqldump.
> From what I can find on the web, this message is generated by an error in the mysql
> code.
> Please correct me if I am wrong.
> Is this fixed in mysql 5.0.27 ?
> Thanks, 
> Connie Logg, Network Analyst
> Stanford Linear Accelerator Center
> ph: 650-926-2879 
> "Happiness is found along the way, not at the end of the road, and 'IF' is the middle
> word in life."


this is not an error but a normal SQL statement with a hint:
/*!40001 SQL_NO_CACHE */ means that MySQL shall not cache this query and 
its corresponding result set. That makes perfect sense because one can 
assume that this statement will be issued just once (by mysqldump) and 
you wouldn't benefit from caching it.

It seems that it takes a long time for this select to complete but there 
are not many ways to improve the situation. Maybe a faster (and 
exclusive) dump device?
Do you use replication? That can help a lot because then
   o you can seperate workload (master) and dump activities (slave)
   o you can silence the slave and dump the slave in a consistent manner 
because no data changes during the dump.
   o you can set up more slaves to spread the workload even more

 From what you told about the completion time of your dump it seems you 
should re-design your whole MySQL setup.


Dr. Frank Ullrich, DBA Netzwerkadministration
Heise Zeitschriften Verlag GmbH & Co KG, Helstorfer Str. 7, D-30625 Hannover
E-Mail: frank.ullrich@stripped
Phone: +49 511 5352 587; FAX: +49 511 5352 538
SELECT /*!40001 SQL_NO_CACHE */ * FROM `ROUTEDATA` messageConnie A. Logg15 Nov
  • Re: SELECT /*!40001 SQL_NO_CACHE */ * FROM `ROUTEDATA` messageDr. Frank Ullrich16 Nov