Domas Mituzas wrote:
Hi!
Don't be so eager.
Replication will break in funny ways when a 5.1 master will get a v5 event.
??? what do you mean?
...if it has v4 slaves
In the best scenario, all mysql4 slaves stop replicating at once, overloading the 5.1 ones and leading the wiki to a halt.
We can run the site off a single slave, usually (well, probably need to send watchlists to blackhole for a while, but.. ;-)
Domas ends up removing the offending statement with a hex editor or upgrading all the slaves in a hurry.
Who in the sane mind upgrades masters before slaves?
Perhaps someone that wants to be able to switch the master back to a mysql4.
Was that a wild idea that if there's no 'upgraded to mysql 5.1' entry in the log, the old mysql4 master was kept as a slave?
Note that I wasn't assuming a setup with the master being the only mysql 5.1, just that still were _some_ v4 slaves. werna has already cleared up that all slaves are also 5.1 so all is good.
Do we have at least one 5.1 slave per 5.1-mastered pool ?
Did we have ever any non-5.1 slave per 5.1-mastered pool?
Domas
When answering, I looked at wikitech but was unable to find the mysql version each slave was running. Consider it a bug #1 issue :)
Aryeh wrote:
You can't replicate from lower versions to higher versions, in general. Only the reverse is safe. So if the master is 5.1, we can assume all the slaves are probably (at least) 5.1.
mysql replicates the sql statements, so I wouldn't be surprised if a mysql5 which only received mysql4 compatible statements worked as master for mysql4s.