Continuous feedback from jenkins console output

This one really was a pain in the ass for a long time.

Jenkins is great, not only for building projects, but I start the most of the ops related tasks here. All the projects have their own workspace, I can browse the previous outputs, see if a task failed or not, and I can easily share the results at the end of the task.

I had only one problem with that: the long-running tasks weren’t shown on console output until they finished. I tried to solve that, but it was only annoying, not a showstopper, so I let that go, because it didn’t look like an easy win, and I didn’t want to spend too much time on that.

But last week I created a job for online altering the database and – surprise! – pt-online-schema-change was continuously updated the console log screen, so I started to google out what is happening.

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Syncing differences in MySQL cluster

In my last post, I showed how to fix replication errors on slaves, but I’ve made a mistake: my current example wasn’t good, after skipping the command or inserting an empty transaction the dataset was different because of a timestamp holding date column which is the CURRENT_TIMESTAMP default. Fixing the error solved the problem of the running replication thread, but the data wasn’t same on the hosts. I decided to leave this as-is, and instead of recreating the test, I rather show how to sync the databases.

For this, we can use the ‘pt-table-checksum’ and ‘pt-table-sync’ utilities from Percona toolkit.

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