Notes

Fun MySQL fact of the day: unsafe logging

Over the last couple weeks, we've been discussing the MySQL binary log and building up our mental mode around the STATEMENT-based binary log format. When using a STATEMENT binary log format, MySQL very simply puts the SQL statement that issued a change into the binary log. Then, when ... read more

Fun MySQL fact of the day: replication lag can be good

We've spent number of days discussing replication delay, and we've mostly considered replication delay as bad. And, true, in most cases, it usually is pretty bad, but today we're going to consider a case when replication delay is as desirable as it is important. ... read more

Fun MySQL fact of the day: absolute delay

Yesterday, we established an understanding of Seconds_Behind_Master and identified some of its shortcomings. While it's not a completely useless metric, it's also not a very helpful one. What we probably really want is an absolute measure of replication latency, and we'll look at one way of accomplishing ... read more

Fun MySQL fact of the day: the SQL thread

Yesterday, we looked at how a MySQL replica's IO thread downloads a master's binary logs and stores them as its own "relay logs". We also said this happens until the IO thread is stopped or the replica database runs out of disk space, and while that's true ... read more

Fun MySQL fact of the day: the IO thread

On Friday, we looked at a pretty fun and very handy use of the MySQL binary log to perform point-in-time recovery during a make-believe disaster. We're going to circle back to point-in-time recovery a bit later this week, but I want to first start looking at MySQL's replication ... read more
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