I don’t use many tools in my consulting practice but for the ones I do, I try to know them as best as I can. I’ve been using mk-query-digest for almost as long as it exists but it continues to surprise me in ways I couldn’t imagine it would. This time I’d like to share a quick tip on how mk-query-digest allows you to slice your data in a completely different way than it otherwise would by default.

Disclaimer: this only works when persistent connections or connection pools aren’t used and is only accurate when single mysql connection is used during execution of a request.

If you are seeking to reduce the load on the database server and [as a result] increase response time for some random user requests, you are usually interested in queries that are consuming most MySQL time and that’s how mk-query-digest groups and …

Here’s the weekly review of Percona Server and XtraBackup news. Before I begin, let me briefly address a common question. We are sometimes asked about our plans in light of developments in the market such as MySQL 5.5, MariaDB, Drizzle, etc. The short answer is that we’re very happy with Oracle’s GPL’ed MySQL releases as a baseline for Percona Server, we think that it is extremely important to continue developing Percona Server, we don’t see the need for any major changes to how we’re doing that right now, and we plan to stay the course. This question has helped us to see the need for a prominent public roadmap for Percona Server’s future, and we will work on creating that, to provide a longer and more detailed answer to this and other questions. Now, on to the news:

In Percona Server news,

• We released Percona Server 5.5.10-20.1 as a Release Candidate. ( …

I’ve presented at two different venues about HandlerSocket recently and the number one question that always arises is:

Why hasn’t HandlerSocket become more popular than it is?

Considering how fast and awesome HandlerSocket is, it’s not seeing as rapid adoption as some might expect. I theorize that there are five reasons for this:

Bugs, Bugs, Bugs

Up until the beginning of the year, HandlerSocket had a couple of bugs that a lot of people considered deal-breakers, and it’s not widely known that these issues have been fixed.

• Write operations do not invalidate the query cache – Exactly what it sounds like, if you performed a write operation via HandlerSocket, you could potentially read stale data from the MySQL interface.
• …

I am happy to announce that Percona Server and Percona XtraBackup are now available for the Solaris platform!

• You can download the latest Percona Server 5.1.55-12.6 stable release from our download area.
• As for Percona XtraBackup, we made Solaris binaries for the upcoming XtraBackup-1.6 release, and they are available from “pre-release” directory.

There are couple features not available in Solaris build of Percona Server: Response Time Distribution (it depends on GCC platform specific functions) , HandlerSocket ( compilation issues on Solaris), Maatkit UDFs.

I want to say a special thanks to Joyent (a cloud computing provider) for Solaris resources and …

Have you ever seen BIG weird numbers in mk-query-digest report that just seem wrong? I have! Here’s one report I got today:

...
# Attribute          total     min     max     avg     95%  stddev  median
# ============     ======= ======= ======= ======= ======= ======= =======
# Exec time          5088s     1us    171s     2ms   467us   104ms    28us
# Lock time            76s       0      3s    26us    69us     3ms       0
# Rows sent          9.80M       0   1.05M    3.50    0.99  642.32       0
# Rows examine       5.59G       0  82.56M   2.00k    0.99  97.41k       0
# Rows affecte     457.30k       0   2.62k    0.16    0.99    1.68       0
# Rows read          2.16G       0  82.56M  788.53   21.45  82.91k    0.99
# Bytes sent         2.14T       0   4.00G 781.27k   3.52k  47.84M   84.10
# Merge passes     273.47G       0   4.00G  97.69k       0  10.35M       0
# Tmp tables …

It’s time for the weekly roundup of news for Percona Server and XtraBackup. To follow up on my note from last week, we’re still checking and validating the download stats. It appears that Percona Server has been downloaded well over 100,000 times, and Percona XtraBackup has been downloaded over 200,000 times. But when we changed the script to separate out the downloads for our 5.5 release series, the overall number came back slightly decreased, which makes no sense. We haven’t had the chance to vet the analysis script yet, but we should be able to do that shortly.

For Percona Server,

• We worked on Solaris builds for the server.
• Peter proposed a feature for the server to enable more efficient incremental backups with XtraBackup.
• Peter, Vadim, and Nickolay continued investigating alternative methods of implementing flush in Percona Server. (I am involved, but not as deeply.) The task is complex and …

Here’s what is new in Percona Server and Percona XtraBackup since last week. We are working on compiling and checking download statistics for both pieces of software. The preliminary numbers are far higher than I thought they would be. Both Percona Server and XtraBackup are becoming amazingly popular. I am aware of deployments running into multiple thousands of instances of Percona Server in some companies.

• Laurynas Biveinis joined the Percona Server project as a developer.
• We continued working on our upcoming Percona Server 5.5 stable release. Vadim has also spent a lot of time benchmarking against MySQL 5.5. Sorry, I can’t reveal how good the numbers are until the benchmarks are fully validated. Watch this blog for Vadim’s announcement.
• We began investigating the effort required to port Percona Server to Windows. We are interested in knowing how many people using MySQL on Windows would be ready to pay …

The xtrabackup compiled C binary (as distinct from XtraBackup, which is the combination of the C binary and the Perl script) has support for printing out stats on InnoDB tables and indexes. This can be useful to examine whether you’d benefit from “defragmenting” your MySQL database with OPTIMIZE TABLE, although I have not determined firm guidelines for when that will actually help. I’ve written a small Perl script that formats the stats output nicely to give an overview of fragmentation.

It’s an initial draft, and if you find issues with it I would like to know so I can fix them. The script is embedded in the documentation page and can be downloaded by clicking on the header at the top of the code listing. The output looks like this:

          TABLE           INDEX TOT_PAGES FREE_PAGES   PCT_FULL
art.link_out104 …

Welcome to the weekly roundup and progress report. What’s new this week in Percona Server:

• As you might have seen, we released Percona Server 5.1.55-12.6. This release also updated our repositories for Debian Squeeze.
• We’re enhancing the PROCESSLIST to include columns for rows examined, sent, and read. This can be useful for understanding how much progress a query has made, and potentially how long until it completes.
• Our 5.5 release is a release candidate at the moment. When it goes to stable status, several command-line options and configuration variables will be renamed. We did not always choose good names for variables and options, and this is the best time to fix that.
• We are working on a new adaptive flushing algorithm that should further improve the quality and consistency of …

Percona Server has a new logo:

Percona Server Logo

Other news for Percona Server:

• Many users noticed that our repositories don’t work for Debian Squeeze, the new version of Debian. Our repositories will support Squeeze on the next release, which will be based on MySQL 5.1.55.
• We merged a fix for InnoDB’s slow DROP TABLE performance. A new option, innodb_lazy_drop_table, controls this behavior.
• Vadim asked Yasufumi to look into porting the innodb_sync_checkpoint_limit feature from the Facebook patches into Percona Server.
• Peter requested a high priority for logging queries to the slow query log from a replica using row-based replication.
• Yasufumi reported a feature request for XtraDB to store statistics for the ::records_in_range() handler function, instead of accessing the data. This could improve performance for complex queries.
• A user on our …