This is a hack I've heard about a couple times now:
Paul wrote a script that reads from the logfile the queries that are going to be executed moments later. He parses the queries and constructs new select queries that populate the cache with the data that speeds up the upcoming writes. He claims, if I remember correctly, a three to four times speed-increase.
Here's the problem in a nutshell. The master can write transactions in parallel but slaves can only write them in series. [1]
This means you have a lot of optimizations on the master (TCQ and NCQ being examples) that aren't possible on the slave.
What this patch would do is precache the data so it's already available in memory. Since you're pre-reading the binary log you can run SELECTs in parallel on the SLAVEs so that the cache is hot when …
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