I've completed a beta implementation of my take on the replication pre-cache tool... Sorry nothing to download yet, I have to get it through an internal committee at Yahoo before I can release it (and you can imagine things are kind of crazy here).  I wrote it myself because:

It's just over 250 lines of Ruby, my new favorite language and fairly compact.  It doesn't use the Ruby Mysql library, rather just IO.popen calls to the mysql command line client.  I did this for two reasons: 

read more

I'm working on an implementation of a mysql slave precache tool as described by Paul Tuckfield at last year's User conference.

I can easily tell where the SQL Thread is currently is reading from in the local relay log, but it's a harder problem to solve when I want to scan ahead in that log some number of binlog entries and find a valid position. I can simply add to the position some number of bytes, but then I have to stop and loop through calls to 'mysqlbinlog' until I get a position that doesn't throw an error.

This turns out to be a pretty expensive operation, and I'm having a problem where by the time I find a good position and can start my precacher, the slave is already past me!

Does anyone have any clever ways to find good binary log positions besides this (this is in