Monday, August 15, 2011

CodeBits - An event of competitive innovation

Codebits 2009 - Pedro and Rupert It was my pleasure and privilege to attend Codebits in 2009. As Roland Bouman says, its talk choice method is based on public voting, and therefore everyone cha have contribute to the schedule. But that is not the main reason for attending this extraordinary event. It is not just a conference. It's an innovation fest. For 1 and 1/2 days, it's a conference, where the speakers are encouraged to bring to their audience the most innovative and inspiring talks. In the afternoon of the second day, the event becomes a competition, where the teams that have registered will have 24 hours to bring a project to completion, and they have to start and finish within the allotted time. The project can be anything, and I have seen quite a lot of exciting stuff rolling live in the huge pavilion: I could hardly ignore robotics, as these little mechanical smurfs were running all over the place and you would have to be careful not to squash them when you walked. There was plenty of occasions for planning of great projects, together with attempts at improving social relations, and mixing up with big brother. There were projects based on 3D printing, and less broad projects like all-seasons keyboards. A very popular session, followed by practical workshops was lock picking. I attended one of them, learned how to pick simple and less simple locks, and I brought home some lockpicking tools. On a more technical level, I was there with Lenz Grimmer and Kai Seidler, we spoke about MySQL and other cool things, and we had lots of fun for three days. Besides the teams hacking away at their projects, there were several teams showcasing technology that had been developed by winners of the previous years, such as 3D television and intelligent phone networks. In short, This was an inspiring event, which I can warmly recommend.

Thursday, August 11, 2011

Usability improvements in Tungsten Replicator 2.0.4

If you love a software product, you should try to improve it, and not be afraid of criticizing it. This principle has guided me with MySQL (where I have submitted many usability bugs, and discussed interface with developers for years), and it proves true for Tungsten Replicator as well. When I started working at Continuent, while I was impressed by the technology, I found the installation procedure and the product logs quite discouraging. I would almost say disturbing. Fortunately, my colleagues have agreed on my usability focus, and we can enjoy some tangible improvements. I have already mentioned the new installation procedure, which requires just one command to install a full master/slave cluster. I would like to show how you can use the new installer to deploy a multiple source replication topology like the following: The first step is to install one master in each node. I can run the commands from node #4, which is the one that will eventually receive the updates from the remote masters, and where I need to install the slave services:
TUNGSTEN_BASE=$HOME/newinst
SERVICES=(alpha bravo charlie delta)
REPLICATOR=$TUNGSTEN_BASE/tungsten/tungsten-replicator/bin/replicator

for N in 1 2 3 4
do
    INDEX=$(($N-1))

  ./tools/tungsten-installer \
    --master-slave \
    --master-host=qa.r$N.continuent.com \
    --datasource-user=tungsten \
    --datasource-password=secret \
    --service-name=${SERVICES[$INDEX]} \
    --home-directory=$TUNGSTEN_BASE \
    --cluster-hosts=qa.r$N.continuent.com \
    --start-and-report
done
The above loop will install a master (remotely or locally) in the four servers. Then I need to create the slave services. To do it, I use the updated configure-service in the tools directory.
TUNGSTEN_TOOLS=$TUNGSTEN_BASE/tungsten/tools
COMMON_OPTIONS='-C -q 
    --local-service-name=delta 
    --role=slave 
    --service-type=remote 
    --allow-bidi-unsafe=true 
    --datasource=qa_r4_continuent_com' 

$TUNGSTEN_TOOLS/configure-service $COMMON_OPTIONS --master-host=qa.r1.continuent.com  alpha 
$TUNGSTEN_TOOLS/configure-service $COMMON_OPTIONS --master-host=qa.r2.continuent.com  bravo
$TUNGSTEN_TOOLS/configure-service $COMMON_OPTIONS --master-host=qa.r3.continuent.com  charlie 

$TUNGSTEN_BASE/tungsten/tungsten-replicator/bin/replicator restart
$TUNGSTEN_BASE/tungsten/tungsten-replicator/bin/trepctl services
These commands create the slave services locally in Delta. After restarting the replicator, a simple test will be creating something different in each master, and check that the data has replicated to the single slave. The latest improvement in matter of usability is the simplification of the replicator logs. Until a few days ago, if you had an error in the replicator, you would get a long list of not exactly helpful stuff. For example, if I create a table in a slave, and then create the same table in the master, I will break replication. The extended log would produce something like this:
INFO   | jvm 1    | 2011/08/11 18:10:52 | 2011-08-11 18:10:52,216 [tsandbox - q-to-dbms-0] ERROR pipeline.SingleThreadStageTask Event application failed: seqno=1 fragno=0 message=java.sql.SQLException: Statement failed on slave but succeeded on master
INFO   | jvm 1    | 2011/08/11 18:10:52 | 2011-08-11 18:10:52,217 [tsandbox - Event dispatcher thread] ERROR management.OpenReplicatorManager Received error notification, shutting down services: Event application failed: seqno=1 fragno=0 message=java.sql.SQLException: Statement failed on slave but succeeded on master
INFO   | jvm 1    | 2011/08/11 18:10:52 | com.continuent.tungsten.replicator.applier.ApplierException: java.sql.SQLException: Statement failed on slave but succeeded on master
INFO   | jvm 1    | 2011/08/11 18:10:52 |       at com.continuent.tungsten.replicator.applier.MySQLDrizzleApplier.applyStatementData(MySQLDrizzleApplier.java:183)
INFO   | jvm 1    | 2011/08/11 18:10:52 |       at com.continuent.tungsten.replicator.applier.JdbcApplier.apply(JdbcApplier.java:1233)
INFO   | jvm 1    | 2011/08/11 18:10:52 |       at com.continuent.tungsten.replicator.applier.ApplierWrapper.apply(ApplierWrapper.java:101)
INFO   | jvm 1    | 2011/08/11 18:10:52 |       at com.continuent.tungsten.replicator.pipeline.SingleThreadStageTask.runTask(SingleThreadStageTask.java:498)
INFO   | jvm 1    | 2011/08/11 18:10:52 |       at com.continuent.tungsten.replicator.pipeline.SingleThreadStageTask.run(SingleThreadStageTask.java:155)
INFO   | jvm 1    | 2011/08/11 18:10:52 |       at java.lang.Thread.run(Unknown Source)
INFO   | jvm 1    | 2011/08/11 18:10:52 | Caused by: java.sql.SQLException: Statement failed on slave but succeeded on master
INFO   | jvm 1    | 2011/08/11 18:10:52 |       at com.continuent.tungsten.replicator.applier.MySQLDrizzleApplier.applyStatementData(MySQLDrizzleApplier.java:139)
INFO   | jvm 1    | 2011/08/11 18:10:52 |       ... 5 more
INFO   | jvm 1    | 2011/08/11 18:10:52 | Caused by: java.sql.SQLSyntaxErrorException: Table 't1' already exists
INFO   | jvm 1    | 2011/08/11 18:10:52 |       at org.drizzle.jdbc.internal.SQLExceptionMapper.get(SQLExceptionMapper.java:78)
INFO   | jvm 1    | 2011/08/11 18:10:52 |       at org.drizzle.jdbc.DrizzleStatement.executeBatch(DrizzleStatement.java:930)
INFO   | jvm 1    | 2011/08/11 18:10:52 |       at com.continuent.tungsten.replicator.applier.MySQLDrizzleApplier.applyStatementData(MySQLDrizzleApplier.java:125)
INFO   | jvm 1    | 2011/08/11 18:10:52 |       ... 5 more
INFO   | jvm 1    | 2011/08/11 18:10:52 | Caused by: org.drizzle.jdbc.internal.common.QueryException: Table 't1' already exists
INFO   | jvm 1    | 2011/08/11 18:10:52 |       at org.drizzle.jdbc.internal.mysql.MySQLProtocol.executeQuery(MySQLProtocol.java:500)
INFO   | jvm 1    | 2011/08/11 18:10:52 |       at org.drizzle.jdbc.internal.mysql.MySQLProtocol.executeBatch(MySQLProtocol.java:546)
INFO   | jvm 1    | 2011/08/11 18:10:52 |       at org.drizzle.jdbc.DrizzleStatement.executeBatch(DrizzleStatement.java:917)
INFO   | jvm 1    | 2011/08/11 18:10:52 |       ... 6 more
INFO   | jvm 1    | 2011/08/11 18:10:52 | 2011-08-11 18:10:52,218 [tsandbox - Event dispatcher thread] WARN  management.OpenReplicatorManager Performing emergency service shutdown
INFO   | jvm 1    | 2011/08/11 18:10:52 | 2011-08-11 18:10:52,219 [tsandbox - Event dispatcher thread] INFO  pipeline.Pipeline Shutting down pipeline: slave
INFO   | jvm 1    | 2011/08/11 18:10:52 | 2011-08-11 18:10:52,219 [tsandbox - q-to-dbms-0] INFO  pipeline.SingleThreadStageTask Terminating processing for stage task thread
INFO   | jvm 1    | 2011/08/11 18:10:52 | 2011-08-11 18:10:52,219 [tsandbox - q-to-dbms-0] INFO  pipeline.SingleThreadStageTask Last successfully processed event prior to termination: seqno=0 eventid=mysql-bin.000002:0000000000000426;20
Did you see the reason for the error? No? Neither did I. I would need to open the THL, look for event #1, and determine what it was. Instead, the new user.log looks like this:
2011-08-11 18:10:52,216 ERROR Received error notification: Event application failed: seqno=1 fragno=0 message=java.sql.SQLException: Statement failed on slave but succeeded on master
Caused by : java.sql.SQLException: Statement failed on slave but succeeded on master
Caused by : Statement failed on slave but succeeded on master
Caused by : Table 't1' already exists
Caused by : Table 't1' already exists
2011-08-11 18:10:54,721 INFO  State changed ONLINE -> OFFLINE:ERROR
2011-08-11 18:10:54,721 WARN  Received irrelevant event for current state: state=OFFLINE:ERROR event=OfflineNotification
That's much better. It is not perfect yet, but it will be soon. Right now, it tells me what is wrong without forcing me to go hunting for it amid hundreds of stack trace lines. Give it a try, using the latest replicator build.

Wednesday, August 10, 2011

Call for disclosure on MySQL Conference 2012

Percona has announced Percona Live MySQL Conference and Expo 2012. Kudos for their vision and entrepreneurship. I have seen comments praising their commitment to the community and their willingness to filling a void. I have to dot a few i's and cross some t's on this matter.

That was not the only game in town.

By the end of June, there were strong clues that O'Reilly was not going to organize a conference. The question of who could fill the void started to pop up. The MySQL Council started exploring the options for a community-driven conference to replace the missing one. The general plan was along the lines of "let's see who is in, and eventually run a conference without the big organizer. If nobody steps up, the IOUG can offer a venue in Las Vegas for an independent MySQL conference". The plan required general consensus among the major players, and therefore we started asking around about availability and participation. Percona did not answer our requests. They delayed the meeting, and in the meantime we continued preparing for the plan B of a conference in Vegas. Then some of us received a message from Percona, pre-announcing a conference in Santa Clara. No offer to gather a broad participation from other entities. No sign of wanting to do a neutral event, i.e. an event not tied to a single company.

Some background

That was puzzling, because I recall vividly how Baron Schwartz and Peter Zaitzev advocated strongly in favor of an independent conference, not so long ago:
The conference is organized and owned by MySQL, not the users. It isn’t a community event. It isn’t about you and me first and foremost. It’s about a company trying to successfully build a business, and other companies paying to be sponsors and show their products in the expo hall.
Baron Schwartz, April 23, 2008.
I would like to see the conference which is focused on the product users interests rather than business interests of any particular company (or personal interests of small group of people), I would like it to be affordable so more people can attend and I’d like to see it open so everyone is invited to contribute and process is as open as possible.
Peter Zaitzev, April 23, 2008.

A call to disclosure

I understand the business motivation to organize a conference with your company name in the title, while at the same time leveraging the wide MySQL community. However, if I have to judge by the organization of previous Percona Live events, I don't see any of the benefits that were advocated three years ago. I see a business conference that is inspired to the same principles that Percona was criticizing in 2008. What is it then? If it is supposed to be a community conference, let's call it "MySQL Conference" and ask for broad participation. There are plenty of people in the community who are willing to help and make the event a success, not only for the benefit of Percona, but for the global benefit of everyone in the ecosystem, including Oracle, the IOUG, and every company with a business related to MySQL. If it is not a community conference, let's state it clearly, so that people can set their expectations accordingly.

Unintended consequences

Someone may think it's a good thing to have a MySQL conference without Oracle participation but I am sure most will agree that it is not desirable. Much as I admire Percona's technical merits, if I go to the conference I want to hear from a wide range of participants. Specifically, I would like to know what's in the pipeline, and I want to hear that from the engineers in the MySQL team, i.e. from Oracle. I doubt that Oracle would send engineers and VPs to talk to a conference that is named after a competitor, and that may be true for other entities, which I (and many others) would like to hear from.

In short

Is this the conference of Baron's and Peter's earlier dreams or is it the fulfillment of their current business strategy?
Please, let the community know.

Disclaimer

The opinions in this post are my own. My employer does not censor my writings and gives me full freedom of expression, but my opinion does not necessarily match that of my company.

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