The replag paranoia is out of hand...
It would help to have more than one person looking at it.
There is no reason that a select should be blocking other reads no matter what the isolation level is.... Mysql had that sort of behavior with ISAM tables, but it should not exist with innodb..
If this is the case, can we *please* ask mysql to fix their software?
If we find the exact problem, sure. At the time, DaB's replication tools where getting transaction timeouts while trying to perform updates. So *something* was locking the tables. It would be great if anyone could tell use what except long running selects could cause this (considering no one else can write to the db).
If setting the default isolation level to dirty *really* does not help, or if it causes *serous* problems to anyone, we should undo it. OTOH, if you rely on a specific transactional behavior, you should probably request it explicitly anyway.
Regards, Daniel
PS: the subject line is so long that it got wrapped into a new header line, and a tab was inserted at the start of the wrapped part. This is compliant with the mail RFC, afaik. But apparently, some clients or MTA's choke on it.