On 10/09/2013 12:27 PM, Marc Schmitzer wrote: > While this works well most of the time, we occasionally have queries > fail with "MySQL server has gone away" errors. We know that the mysqld > process has indeed *not* gone away, and re-opening the connection works.
Ok, this appears to be caused by the wait_timeout option of the MySQL server[1], which defaults to 8 hours. If you are unwilling/unable to change the server config, there are at least two ways of working around this: 1) Setting the "reconnect" option on the mysql connection. Unfortunately, this is not supported by the Qt-API (not even QSqlDatabase::setConnectOptions) and requires fetching the raw MYSQL* handle from the QSqlDriver and using mysql_options() from libmysqlclient. 2) Since the wait_timeout is an *idle* timeout, the connection can presumably be kept alive by making regular dummy queries. [1] http://dev.mysql.com/doc/refman/5.0/en/server-system-variables.html#sysvar_wait_timeout -- Mit freundlichen Gruessen / Best regards Marc Schmitzer SW-Entwicklung ESWL / ESWT Software development ESWL / ESWT ***************************************************************** Richard Wolf GmbH Pforzheimer Strasse 32 75438 Knittlingen Tel.: +49 7043 35-1107 Fax: +49 7043 35-1255 Email: marc.schmit...@richard-wolf.com Web: http://www.richard-wolf.com ***************************************************************** +++ Richard Wolf GmbH, Pforzheimer Strasse 32, 75438 Knittlingen Managing Directors: Siegfried Karst, Juergen Pfab, Juergen Steinbeck. Trade Register: Mannheim HRB 510031 +++ Richard Wolf GmbH routinely monitors the content of e-mail sent and received via its network for the purposes of ensuring compliance with its policies and procedures. Richard Wolf GmbH is not responsible for any changes made to the message after it has been sent. Where opinions are expressed, they are not necessarily those of Richard Wolf GmbH. This e-mail and any files transmitted with it are confidential and intended solely for the use of the individual or entity to which they are addressed. If you are not the intended addressee, or the person responsible for delivering it to them, you may not copy, forward, disclose, or otherwise use it or any part of it in any way. To do so may be unlawful. If you receive this e-mail by mistake, please advise the sender immediately. +++ _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
