Posts by Gerry Narvaja

What Exactly is Swappiness?

This is an issue that keeps rearing its ugly head over and over again, and since it greatly affects performance, it is most important that DBAs of any DMBS running on Linux come to grips with it. So I decided to do some research and try different settings on my notebook. Here are my findings.

MySQL: Using CONNECT to Quickly Verify Replication Health

One very helpful use of the technique Sheeri described in Remote connections without leaving the mysql shell is making sure that replication is working properly. According to the MySQL Reference Manual’s section on SHOW SLAVE STATUS Syntax, it shows information corresponding to the slave thread in the slave server. When replication is broken, however, or not working properly due to network issues between master and slave, this information may not be accurate. This has improved over recent releases, but it’s still not perfect. The question, then, is: how to be 100% sure (or as close as you can get to 100%) that replication is running fine? The answer, as offered by Sheeri: use CONNECT.

Three Clever MySQL Diagnostic Tools

Last week I had to confront one of those situations where you can’t really tell what is going on with a piece of software, and the final conclusion would sound completely crazy if postulated as the initial hypothesis. The regular MySQL commands and utilities fall short in these cases, so I had to resort to the three tools reviewed in this article.

MySQL Reference Manual Search

Martin Brown’s blog shows a pretty good way of navigating the MySQL Reference Manual. It’s worth noting, however, that finding the different topics has been a lot easier since mysql.com started using a Google appliance for its search. With the new search capabilities, I just type any term in the Search Manual box on the left and hit Go. So far it has hit the bulls-eye every single time, saving me a lot of effort getting what I need. his feature has long been on the wish-list of those of us who regularly work with the MySQL on-line manual. Try it out.

Gigantic IN Clauses

Over the last few weeks I’ve been looking at several customers’ slow query logs, and I found in many of them an odd type of query. These are SELECT statements that contain an IN clause that includes dozens, sometimes hundreds of values. These statements often end in the slow query log. I’m not sure if these queries are this way by design or if they are generated by a specific database development tool. What’s your experience with these kind of expressions? I’d love to learn where do these gigantic IN clauses come from and hear some use-cases.

Maatkit Options for Restoring a Slave or Master

The Maatkit toolkit is a real blessing for the MySQL DBA. And while its documentation is pretty good, in some cases it’s necessary to read carefully a second and third time to make sure you are not missing an important piece of information. In this article I will comment on mk-table-chksum and mk-table-sync. My comments are mostly aimed at those DBAs who are considering using these utilities with medium or larger-sized databases.

Printing Multiple Pages With MySQL Workbench, Community Edition

A few days back I read the Workbench Team’s blog and was curious about the printing capabilities of MySQL Workbench Community edition. As we already know by now, it only allows you to print a single page. I needed to review a customer query which had several tables and some complicated relationships, so I decided to take Workbench Community for a spin (I already knew the Standard edition from my previous job) and tested the following steps…Here’s where the heavy testing started. Besides the PDF file I also created an SVG and an EPS. All of these are scalable. My thinking was that if I imported these files into the right tools, I should be able to get a bigger printout.

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