Jim/Jaime What engine are you implementing?/ Qual mecanismo de MySQL que você está implementando? Saludos desde Sud America Martín
> Date: Wed, 20 Aug 2014 13:54:46 -0300 > Subject: Re: inconsistent optimization > From: edua...@gerencianet.com.br > To: j...@lowcarbfriends.com > CC: mysql@lists.mysql.com > > Well, > > Try to start checking the IOPs vs Disc. Check your iowait and the cache > size. > > Could you send a "create table" and the query for us? > > > > > > Atenciosamente, > > *Eduardo Fontinelle* > *Chief Technology Officer | G**erencianet* > Phone: +55 (31) 3603-0812 > > > > 2014-08-20 12:04 GMT-03:00 Jim <j...@lowcarbfriends.com>: > > > Without going into specific details on queries... > > > > Using mysql 5.1 as provided with CentOS6, I've noticed some queries > > providing what I can best explain as inconsistent optimization. The > > database can be quieted to just controlled queries and at times the same > > query will return very quickly when at other times may take minutes. > > > > I don't see the same behavior with mysql5.0 under CentOS5. The same > > queries on the same data returns quickly consistently. > > > > When the queries run slowly they show in a process list as either in a > > "copy to temp table" or "sending data" state. At first I thought query > > restructuring to avoid the copy to temp table was a path to a solution, but > > now I don't think so since the same query changed so that it no longer > > needs a temp table will sit in the "sending data" state for a long time. > > > > The queries do eventually come back with correct results, but it takes > > minutes rather than milliseconds (sometimes slow; sometimes fast). > > > > Have others seen this behavior? Any explanations? > > Any reading to point to for further understanding? > > > > Thanks. > > > > -- > > MySQL General Mailing List > > For list archives: http://lists.mysql.com/mysql > > To unsubscribe: http://lists.mysql.com/mysql > > > >
