MySQL Cluster Manager 1.2.3 Released

MySQL Cluster Manager 1.2.3 is now available to download from My Oracle Support.

Details on the changes can be found in the MySQL Cluster Manager documentation .

Documentation is available here.

MySQL Cluster 7.3 DMR2 – Includes MySQL Cluster Auto-Installer

The second Development Milestone Release for MySQL Cluster 7.3 has just been released – download it from the development tab on this page.

Deploying a well configured cluster has just got a lot easier! Oracle have released a new auto-installer/configurator for MySQL Cluster that makes the processes extremely simple while making sure that the cluster is well configured for your application. The installer is part of the latest MySQL Cluster 7.3 Development Milestone Release and so is not yet GA but it can also be used on MySQL Cluster 7.2 (which is GA). A single command launches the web-based wizard which then steps you through configuring the cluster; to keep things even simpler, it will automatically detect the resources on your target machines and use these results together with the type of workload you specify in order to determine values for the key configuration parameters.

For a broader view of what is being released – check out this MySQL Cluster 7.3.1 DMR article.

Tutorial Video

Before going through the detailed steps, here’s a demonstration of the auto-installer in action (note that this is actually an earlier version but the idea is the same)…

Downloading and running the wizard

The software can be downloaded as part of the MySQL Cluster package from the “Development Releases” tab at MySQL Cluster DMR Download. To run on Windows, just double click setup.bat – note that if you installed from the MSI and didn’t change the install directory then this will be located somewhere like C:\Program Files (x86)\MySQL\MySQL Cluster 7.3. On Linux, just run ndb_setup from the bin folder.

If you launch the installer from a desktop environment then the first page of the wizard will automatically be opened in your web browser, if not then just browse to the URL that is displayed on the command line.

Creating your cluster

Figure 1 Specify hosts and application type

Figure 2 Auto-discovery of host resources

It’s also on this page that you can specify where the MySQL Cluster software is stored on each of the hosts (if the defaults aren’t correct) – this should be the path to where you extracted the MySQL Cluster tar-ball file – as well as where the data (and configuration files) should be stored. You can just overwrite the values or select multiple rows and hit the “edit” button.

Figure 3 Review Cluster topology

Alternatively, you can add extra nodes, move nodes from one host to another (just drag and drop), delete nodes or change a node from one type to another.

Figure 4 Review configuration parameters

Figure 5 Deploy the Cluster

If you prefer or need to start the processes manually, this page also shows you the commands that you’d need to run (as well as the configuration files if you need to create them manually).

A traffic light display shows the various Cluster nodes (processes) coming into service.

Figure 6: Confirm that all nodes are running

As always it would be great to hear some feedback especially if you’ve ideas on improving it or if you hit any problems.

Foreign Keys in MySQL Cluster

Foreign Key constraints between tables

The newly announced second MySQL Cluster 7.3 Development Milestone Release (7.3.1 m2) builds upon first DMR (7.3.0 m1) released last year which added Foreign Keys to MySQL Cluster. Foreign Keys is a feature requested by many, many people and has often been cited as the reason for not being able to replace InnoDB with MySQL Cluster when they needed the extra availability or scalability. While this functionality is not yet Generally Available (i.e. you shouldn’t deploy your application on it yet) you can can try it out by downloading the binaries from http://dev.mysql.com/downloads/cluster/ and selecting the “Development Releases” tab. Please let us have your feedback so that we know what to improve.

For a broader view of what is being released – check out this MySQL Cluster 7.3.1 DMR article.

Note that this post is an up-version of the original – and was first published with the 7.3 labs release in June 2012.

What’s a Foreign Key

The majority of readers who are already familiar with Foreign Keys can skip to the next section.

Foreign Keys are a way of implementing relationships/constraints between columns in different tables. For example, in the above figure, we want to make sure that the value of the county column in the towns table has an associated entry in the counties table. In this way, no-one can place a town in a non-existent county and similarly no one can remove a county and leave orphaned towns behind.

We refer to the towns table as the child and the counties table as the parent.

There are different categories of constraints that influence how they’re enforced when a row is updated or deleted from the parent table:

• Cascade: If a row is deleted from the parent then any rows in the child table with a matching FK value will also be deleted. Similarly for changes to the value in the parent table.
• Restrict: A row cannot be deleted from the parent table if this would break a FK constraint with the child table. Similarly for changes to the value in the parent table.
• No Action: Very similar to “Restrict” except that any events/triggers on the parent table will be executed before the constraint is enforced – giving the application writer the option to resolve any FK constraint conflicts using a stored procedure.
• Set NULL: If NULL is a permitted value for the FK column in the child table then it will be set to NULL if the associated data in the parent table is updated or deleted.
• Set Default: If there is a default value for the FK column in the child table then it will be used if the associated data in the parent table is updated or deleted. Note that this is not implemented in this version – the constraint can be added to the schema but any subsequent deletion or update to the column in the parent table will fail.

How to use Foreign Keys with MySQL Cluster

For anyone familiar with using FKs with InnoDB, a lot of this will be very similar – that’s intentional in the design of this Cluster feature. Throughout this section we will use the tables shown in the above figure.

First of all, create the tables and add some data:

mysql> CREATE DATABASE clusterdb;USE clusterdb;
mysql> CREATE TABLE counties (county VARCHAR(30) NOT NULL PRIMARY KEY, country VARCHAR(30))
  ENGINE=ndb;
mysql> INSERT INTO counties VALUES ('Berkshire','England'),('Shropshire','England'),
  ('Oxfordshire','England'),('Buckinghamshire','England');
mysql> CREATE TABLE towns (town VARCHAR(30) NOT NULL PRIMARY KEY, county VARCHAR(30),
  INDEX county_county_index (county), CONSTRAINT county_town FOREIGN KEY (county) 
  REFERENCES counties(county) ON DELETE RESTRICT ON UPDATE RESTRICT) ENGINE=ndb;
mysql> INSERT INTO towns VALUES ('Maidenhead','Berkshire'),('Reading','Berkshire'),
  ('Shrewsbury','Shropshire'),('Oxford','Oxfordshire');
mysql> SELECT * FROM counties;SELECT * FROM towns;
+-----------------+---------+
| county          | country |
+-----------------+---------+
| Shropshire      | England |
| Buckinghamshire | England |
| Berkshire       | England |
| Oxfordshire     | England |
+-----------------+---------+
4 rows in set (0.00 sec)

+------------+-------------+
| town       | county      |
+------------+-------------+
| Reading    | Berkshire   |
| Shrewsbury | Shropshire  |
| Maidenhead | Berkshire   |
| Oxford     | Oxfordshire |
+------------+-------------+
4 rows in set (0.00 sec)

Note that the FK is actually defined as part of creating the towns table with CONSTRAINT county_town FOREIGN KEY (county) REFERENCES counties(county) ON DELETE RESTRICT ON UPDATE RESTRICT. county_town is the label assigned to the constraint (if you don’t specify one then one will be automatically created – you can see it by executing SHOW CREATE TABLE towns). The constraint is set up from the county column in the towns (child) table to the county column in the counties (parent) table.

As a first check, we can confirm that values that are not part of the constraint can be modified in the parent table – in this case we’ll move the England/Wales border:

mysql> UPDATE counties SET country='WALES' WHERE county='Shropshire';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

Next, to illustrate the kind of user error that can be prevented, we attempt to add a town in a county that has not yet been defined – we want this to fail as it would break the constraint we created:

mysql> INSERT towns VALUES ('Cambridge','Cambridgeshire');
ERROR 1452 (23000): Cannot add or update a child row: a foreign key constraint fails
  (Unknown error code)
mysql> SHOW WARNINGS;
+---------+------+---------------------------------------------------------------------------------------+
| Level   | Code | Message                                                                               |
+---------+------+---------------------------------------------------------------------------------------+
| Warning | 1296 | Got error 255 'Foreign key constaint violated: No parent row found' from NDB          |
| Error   | 1452 | Cannot add or update a child row: a foreign key constraint fails (Unknown error code) |
+---------+------+---------------------------------------------------------------------------------------+
2 rows in set (0.00 sec)

We can also confirm that the constraint checking works in the opposite direction, by attempting to delete a county that has towns defined for it:

mysql> DELETE FROM counties WHERE county='Berkshire';
ERROR 1451 (23000): Cannot delete or update a parent row: a foreign key constraint fails (Unknown error code)
mysql> SHOW WARNINGS;
+---------+------+-------------------------------------------------------------------------------------------+
| Level   | Code | Message                                                                                   |
+---------+------+-------------------------------------------------------------------------------------------+
| Warning | 1296 | Got error 256 'Foreign key constaint violated: Referenced row exists' from NDB            |
| Error   | 1451 | Cannot delete or update a parent row: a foreign key constraint fails (Unknown error code) |
+---------+------+-------------------------------------------------------------------------------------------+
2 rows in set (0.00 sec)

It is also possible to delete FK constraints and add new ones, we do that next and at the same time we’ll switch to a CASCADE restriction. Note that adding and deleting FKs are on-line operations. In case you have forgotten the name of the constraint (or we had not explicitly named it) we can use the SHOW CREATE TABLE command to remind us:

mysql> SHOW CREATE TABLE towns;
+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                                                                                                                                                                                                                                                                 |
+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| towns | CREATE TABLE `towns` (
  `town` varchar(30) NOT NULL,
  `county` varchar(30) DEFAULT NULL,
  PRIMARY KEY (`town`),
  KEY `county_county_index` (`county`),
CONSTRAINT `county_town` FOREIGN KEY(`county`) REFERENCES `counties` (`county`)
  ON DELETE RESTRICT ON UPDATE RESTRICT
) ENGINE=ndbcluster DEFAULT CHARSET=latin1 |
+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> ALTER TABLE towns DROP FOREIGN KEY county_town;
Query OK, 0 rows affected (0.47 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> ALTER TABLE towns ADD CONSTRAINT county_town FOREIGN KEY (county)
  REFERENCES counties(county) ON DELETE CASCADE ON UPDATE CASCADE;

The data in the tables will not have changed as part of dropping and adding constraints and so you can always DROP and the re-add constraints if you need to turn FKs off for a while:

mysql> SELECT * FROM counties;SELECT * FROM towns;
+-----------------+---------+
| county          | country |
+-----------------+---------+
| Buckinghamshire | England |
| Berkshire       | England |
| Oxfordshire     | England |
| Shropshire      | WALES   |
+-----------------+---------+
4 rows in set (0.00 sec)

+------------+-------------+
| town       | county      |
+------------+-------------+
| Reading    | Berkshire   |
| Shrewsbury | Shropshire  |
| Maidenhead | Berkshire   |
| Oxford     | Oxfordshire |
+------------+-------------+
4 rows in set (0.00 sec)

Now if we delete the county of Berkshire then the CASCADE option will cause all of the associated towns to be deleted too:

mysql> DELETE FROM counties WHERE county='Berkshire';
Query OK, 1 row affected (0.00 sec)

mysql> SELECT * FROM counties;SELECT * FROM towns;
+-----------------+---------+
| county          | country |
+-----------------+---------+
| Shropshire      | WALES   |
| Buckinghamshire | England |
| Oxfordshire     | England |
+-----------------+---------+
3 rows in set (0.00 sec)

+------------+-------------+
| town       | county      |
+------------+-------------+
| Shrewsbury | Shropshire  |
| Oxford     | Oxfordshire |
+------------+-------------+
2 rows in set (0.00 sec)

Note that MySQL Cluster implements FKs in the data nodes and the constraints will be enforced regardless of how the data is written (through SQL, javascript, Memcached, ClusterJ, REST or directly through the NDB API). Before illustrating this, we add back the data we have just deleted:

mysql> INSERT INTO counties VALUES ('Berkshire','England');
Query OK, 1 row affected (0.00 sec)

mysql> INSERT INTO towns VALUES ('Maidenhead','Berkshire'),('Reading','Berkshire');
Query OK, 2 rows affected (0.00 sec)
Records: 2  Duplicates: 0  Warnings: 0

mysql> SELECT * FROM counties;SELECT * FROM towns;
+-----------------+---------+
| county          | country |
+-----------------+---------+
| Shropshire      | WALES   |
| Buckinghamshire | England |
| Berkshire       | England |
| Oxfordshire     | England |
+-----------------+---------+
4 rows in set (0.00 sec)

+------------+-------------+
| town       | county      |
+------------+-------------+
| Reading    | Berkshire   |
| Shrewsbury | Shropshire  |
| Maidenhead | Berkshire   |
| Oxford     | Oxfordshire |
+------------+-------------+
4 rows in set (0.00 sec)

We’ll then run a simple C++ app to delete the ‘Berkshire’ row from the counties table. The full source for the app is available here but the key part of the code is this:

static void do_change(Ndb &myNdb)
{
const NdbDictionary::Dictionary* myDict= myNdb.getDictionary();
const NdbDictionary::Table *countiesTable= myDict->getTable("counties");

char royalBorough[255];
royalBorough[0]=9;
strcpy(royalBorough + 1, "Berkshire");

if (countiesTable == NULL)
APIERROR(myDict->getNdbError());

NdbTransaction *myTransaction= myNdb.startTransaction();
if (myTransaction == NULL) APIERROR(myNdb.getNdbError());

NdbOperation *myOperation= myTransaction->getNdbOperation(countiesTable);
if (myOperation == NULL) APIERROR(myTransaction->getNdbError());

std::cout << "About to delete " << royalBorough << "\n";

myOperation->deleteTuple(); 

myOperation->equal("county", (const char *) royalBorough);

if (myTransaction->execute( NdbTransaction::Commit ) == -1)
APIERROR(myTransaction->getNdbError());

myNdb.closeTransaction(myTransaction);
}

We then run this code and confirm that the cascaded delete has worked:

billy@ws2:~/projects/fk$ ./testfk localhost:1186
About to delete         Berkshire

mysql> SELECT * FROM counties;SELECT * FROM towns;
+-----------------+---------+
| county          | country |
+-----------------+---------+
| Shropshire      | WALES   |
| Buckinghamshire | England |
| Oxfordshire     | England |
+-----------------+---------+
3 rows in set (0.00 sec)

+------------+-------------+
| town       | county      |
+------------+-------------+
| Shrewsbury | Shropshire  |
| Oxford     | Oxfordshire |
+------------+-------------+
2 rows in set (0.00 sec)

Comparison with InnoDB’s Foreign Keys

As mentioned, we’ve attempted to mirror the way that InnoDB works as much as possible in the way that it implements Foreign Keys as that’s what we think will allow people to move more easily to MySQL Cluster when appropriate. There are a couple of exceptions though:

• InnoDB doesn’t support “No Action” constraints, MySQL Cluster does
• You can choose to suspend FK constraint enforcement with InnoDB using the FOREIGN_KEY_CHECKS parameter; MySQL Cluster ignores that parameter. This causes issues as some tools rely on this in order to avoid needing to define FKs and/or populate data in the correct order – examples are database restore and adding multiple FKs using MySQL Workbench. This is something to be addressed in the GA version.
• You cannot set up FKs between 2 tables where one is stored using MySQL Cluster and the other InnoDB.
• You cannot change primary keys through the NDB API which means that the MySQL Server actually has to simulate such operations by deleting and re-adding the row. If the PK in the parent table has a FK constraint on it then this causes non-ideal behaviour. With Restrict or No Action constraints, the change will result in an error. With Cascaded constraints, you’d want the rows in the child table to be updated with the new FK value but, the implicit delete of the row from the parent table would remove the associated rows from the child table and the subsequent implicit insert into the parent wouldn’t reinstate the child rows. For this reason, an attempt to add an ON UPDATE CASCADE where the parent column is a primary key will be rejected.

MySQL Workbench

Viewing and updating Foreign Key Constraints in MySQL Workbench

Closing remarks

This DMR gives you a look at this important new feature that the MySQL engineering team have been working on. We believe that this is going to enable a whole new set of applications exploit the advantages of MySQL Cluster (on-line scalability, real-time performance, NoSQL APIs, real-time performance, on-line schema changes,…) either because:

• they want to simplify their application by pushing these referential checks down into the database – letting the developer focus more of their time on extending the application;
• because they’re stuck with 3rd party middleware that is dependent on FKs
• or that the application is already so dependent on FKs that it would be too much pain to remove them.

It is important to note that this software is not production ready and you should be using MySQL Cluster 7.2 for any live deployments.

If you are new to MySQL Cluster then here are some useful resources to get you started:

• MySQL Cluster Auto-Installer; browser based GUI to get a well configured cluster up and running within minutes
• Get the most out of your MySQL Cluster evaluation

MySQL Cluster 7.2.12 Released

The binary version for MySQL Cluster 7.2.12 has now been made available at http://www.mysql.com/downloads/cluster/ (GPL version) and should soon be available at https://support.oracle.com/ (commercial version).

A description of all of the changes (fixes) that have gone into MySQL Cluster 7.2.12 (compared to 7.2.10) is available from the 7.2.12 Change log.

MySQL Presentations from FOSDEM 2013

FOSDEM 2013

I attended for the first time over the weekend and was really impressed by the number of people there, the energy and the quality of the content. The event really lives up to it’s name and is very developer-focused.

In the end, I got the opportunity to make 2 presentations. The first is a general introduction to MySQL Cluster….

The second illustrates how you can realise the benefits promised by NoSQL data stores wihtout losing the consistency and flexibility of relational databases…

“MySQL & Friends devroom” at FOSDEM 2013

FOSDEM 2013

FOSDEM 2013 is a free event and there’s no requirement to pre-register – just get yourself along to Brussels.

This year I’ll be making a presentation introducing MySQL Cluster. Several of my colleagues from Oracle will also be there to present on the latest and greatest MySQL capabilities – including what’s coming in MySQL 5.6. This will be a great opportunity to politely listen to some real technical experts but an even better one to pester them for extra details – whether during the presentations or when you can grab them at other times.

Hope to see some of you there!

MySQL Cluster Manager 1.2.2 released

MySQL Cluster Manager 1.2.2 is now available to download from E-delivery and from My Oracle Support .

Details on the changes can be found in the MySQL Cluster Manager documentation . Please give it a try and let me know what you think.

Documentation is available here.

MySQL Cluster 7.2.10 Released

The binary version for MySQL Cluster 7.2.10 has now been made available at http://www.mysql.com/downloads/cluster/ (GPL version) or https://support.oracle.com/ (commercial version).

A description of all of the changes (fixes) that have gone into MySQL Cluster 7.2.10 (compared to 7.2.9) is available from the 7.2.10 Change log.

MySQL Cluster 7.2.9 Released

The binary version for MySQL Cluster 7.2.9 has now been made available at http://www.mysql.com/downloads/cluster/ (GPL version) or https://support.oracle.com/ (commercial version).

A description of all of the changes (fixes) that have gone into MySQL Cluster 7.2.9 (compared to 7.2.8) is available from the 7.2.9 Change log.

MySQL Cluster Auto-Installer – labs release

Deploying a well configured cluster has just got a lot easier! Oracle have released a new auto-installer/configurator for MySQL Cluster that makes the processes extremely simple while making sure that the cluster is well configured for your application. The installer is part of MySQL Cluster 7.3 and so is not yet GA but it can also be used on MySQL Cluster 7.2. A single command launches the web-based wizard which then steps you through configuring the cluster; to keep things even simpler, it will automatically detect the resources on your target machines and use these results together with the type of workload you specify in order to determine values for the key configuration parameters.

Tutorial Video

Before going through the detailed steps, here’s a demonstration of the auto-installer in action…

Downloading and running the wizard

The software can be downloaded from MySQL Labs; just select the MySQL-Cluster-Auto-Installer build, unzip the file and then run. To run on Windows, just double click setup.bat – note that if you installed from the MSI and didn’t change the install directory then this will be located somewhere like C:\Program Files (x86)\MySQL\MySQL Cluster 7.2. On Linux, just run ndb_setup.

Creating your cluster

Landing page

From the landing page, just click on the “Create new MySQL Cluster” icon to get started.

On the next page you need to specify the list of servers that will form part of the cluster. The machine where the installer is being run from needs to have ssh access to all of the cluster hosts (further, access to those machines must already have been approved from this one – if you’re uncertain, just manually connect to each one using an ssh client.

By default, the wizard assumes that ssh keys have been set up (so that a password isn't needed) - if that isn't the case, just un-check the checkbox and provide your username and password.

On this page, you also get to specify what "type" of cluster you want; if you're experimenting for the first time then it's probably safest to stick with "Simple testing" but for a production system you'd want to specify the kind of application and whether it will a write-intensive application.

Auto-discovery of target host resources

You can also overwrite the resource-values (for example, if you don't want the cluster to use up a big share of the memory on the target systems then just overwrite the amount of memory.

Overwriting the default directories on the target systems

Defining processes

• Add extra nodes
• Move nodes from one host to another (just drag and drop)
• Delete nodes
• Change a node from one type to another

Add process

Optionally override recommended configuration parameters

Deployment in progress

If for some reason you prefer or need to start the processes manually, this page also shows you the commands that you'd need to run (as well as the configuration files if you need to create them manually).

Once the wizard declares the process complete, you can check for yourself before going ahead and start your testing:

billy@black:~ $ ndb_mgm -e show
Connected to Management Server at: localhost:1186
Cluster Configuration
---------------------
[ndbd(NDB)]     2 node(s)
id=1    @192.168.1.106  (mysql-5.5.25 ndb-7.2.8, Nodegroup: 0, Master)
id=2    @192.168.1.107  (mysql-5.5.25 ndb-7.2.8, Nodegroup: 0)

[ndb_mgmd(MGM)] 2 node(s)
id=49   @192.168.1.104  (mysql-5.5.25 ndb-7.2.8)
id=52   @192.168.1.105  (mysql-5.5.25 ndb-7.2.8)

[mysqld(API)]   9 node(s)
id=50 (not connected, accepting connect from 192.168.1.104)
id=51 (not connected, accepting connect from 192.168.1.104)
id=53 (not connected, accepting connect from 192.168.1.105)
id=54 (not connected, accepting connect from 192.168.1.105)
id=55   @192.168.1.104  (mysql-5.5.25 ndb-7.2.8)
id=56   @192.168.1.104  (mysql-5.5.25 ndb-7.2.8)
id=57   @192.168.1.105  (mysql-5.5.25 ndb-7.2.8)
id=58   @192.168.1.105  (mysql-5.5.25 ndb-7.2.8)
id=59   @192.168.1.106  (mysql-5.5.25 ndb-7.2.8)

As always it would be great to hear some feedback especially if you've ideas on improving it or if you hit any problems.

MySQL Cluster 7.2.8 Released

The binary version for MySQL Cluster 7.2.8 has now been made available at http://www.mysql.com/downloads/cluster/ (GPL version) or https://support.oracle.com/ (commercial version).

A description of all of the changes (fixes) that have gone into MySQL Cluster 7.2.8 (compared to 7.2.7) is available from the 7.2.8 Change log.

MySQL Cluster 7.1.23 has been released

The binary & source versions for MySQL Cluster 7.1.23 have now been made available at https://www.mysql.com/downloads/cluster/7.1.html#downloads (GPL version) or https://support.oracle.com/ (commercial version).

A description of all of the changes (fixes) that have gone into MySQL Cluster 7.1.23 (compared to 7.1.22) are available from the 7.1.23 Change log.

MySQL Cluster 7.2.7 released

The binary version for MySQL Cluster 7.2.7 has now been made available at http://www.mysql.com/downloads/cluster/ (GPL version) or https://support.oracle.com/ (commercial version).

A description of all of the changes (fixes) that have gone into MySQL Cluster 7.2.7 (compared to 7.2.6) are available from the 7.2.7 Change log.

Optimizing Performance of the MySQL Cluster Database – White Paper update

Engineering threads within a Data Node

This paper steps you through:

• Identifying if your application is a good fit for MySQL Cluster
• Measuring performance and identifying problem performance areas to address
• Optimizing performance:
  • Access patterns
  • Using Adaptive Query Localization for complex Joins
  • Distribution aware applications
  • Batching operations
  • Schema optimizations
  • Query optimization
  • Parameter tuning
  • Connection pools
  • Multi-Threaded Data Nodes
  • Alternative APIs
  • Hardware enhancements
  • Miscellaneous
• Scaling MySQL Cluster by Adding Nodes

As well as the kind of regular updates that are needed from time to time, this version includes the extra opportunities for optimizations that are available with MySQL Cluster 7.2 such as faster joins and engineering the threads within a multi-threaded data node.

As a reminder, I’ll be covering much of this material in an upcoming webinar.

MySQL Connect & Oracle OpenWorld 2012

Oracle OpenWorld 2012

The sessions I’ll be involved with are:

• MySQL Cluster – From Zero to One Billion in Five Easy Steps: Of course it takes more than five steps to scale to more than one billion queries per minute, but the new configuration features of MySQL Cluster make it much simpler to provision and deploy MySQL Cluster on-premises or in the cloud, automatically optimized for your target use case. This BoF session is designed to give you a demo of the new features, showing how you can use them to quickly build your own proof of concept and then take that into production. The MySQL Cluster Engineering team will be on hand to answer your questions and also listen to the requirements you have for current or future MySQL Cluster projects. This is Birds-of-a-Feather session and is part of the MySQL Connect conference.
• Developing High-Throughput Services with NoSQL APIs to InnoDB and MySQL Cluster: Ever-increasing performance demands of Web-based services have generated significant interest in providing NoSQL access methods to MySQL (MySQL Cluster from Oracle and the InnoDB storage engine of MySQL), enabling users to maintain all the advantages of their existing relational databases while providing blazing-fast performance for simple queries. Get the best of both worlds: persistence; consistency; rich SQL queries; high availability; scalability; and simple, flexible APIs and schemas for agile development. This session describes the memcached connectors and examines some use cases for how MySQL and memcached fit together in application architectures. It does the same for the newest MySQL Cluster native connector, an easy-to-use, fully asynchronous connector for Node.js. This is a conference session and is part of the MySQL Connect conference.
• Introduction to MySQL High-Availability Solutions: Databases are the center of today’s Web and enterprise applications, storing and protecting an organization’s most valuable assets and supporting business-critical applications. Just minutes of downtime can result in dissatisfied customers and significant loss of revenue. Ensuring database high availability is therefore a top priority for any organization. Attend this session to learn more about delivering high availability for MySQL-based services. It covers
  • The cause, effect, and impact of downtime
  • A methodology for mapping applications to the right high-availability solution
  • An overview of MySQL high availability, from replication to virtualization, clustering, and multisite redundancy
  • Operational best practices to ensure business continuity

  This is a conference session and is part of Oracle OpenWorld.

Early bird pricing is available for the MySQL Connect until 13th July – same date for Oracle OpenWorld.

MySQL Cluster running on Raspberry Pi

MySQL Cluster running on Raspberry Pi

I start a long weekend tonight and it’s the kids’ last day of school before their school holidays and so last night felt like the right time to play a bit. This week I received my Raspberry Pi – if you haven’t heard of it then you should take a look at the Raspberry Pi FAQ - basically it’s a ridiculously cheap ($25 or $35 if you want the top of the range model) ARM based PC that’s the size of a credit card.

A knew I had to have one to play with but what to do with it? Why not start by porting MySQL Cluster onto it? We always claim that Cluster runs on commodity hardware – surely this would be the ultimate test of that claim.

I chose the customised version of Debian – you have to copy it onto the SD memory card that acts as the storage for the Pi. Once up and running on the Pi, the first step was to increase the size of the main storage partition – it starts at about 2 Gbytes – using gparted. I then had to compile MySQL Cluster – ARM isn’t a supported platform and so there are no pre-built binaries. I needed to install a couple of packages before I could get very far:

sudo apt-get update
sudo apt-get install cmake
sudo apt-get install libncurses5-dev

Compilation initially got about 80% through before failing and so if you try this yourself then save yourself some time by applying the patch from this bug report before starting. The build scripts wouldn’t work but I was able to just run make…

make
sudo make install

As I knew that memory was tight I tried to come up with a config.ini file that cut down on how much memory would be needed (note that 192.168.1.122 is the Raspberry Pi while 192.168.1.118 is an 8GByte Linux x86-64 PC – doesn’t seem a very fair match!):

[ndb_mgmd]
hostname=192.168.1.122
NodeId=1

[ndbd default]
noofreplicas=2
DataMemory=2M
IndexMemory=1M
DiskPageBufferMemory=4M
StringMemory=5
MaxNoOfConcurrentOperations=1K
MaxNoOfConcurrentTransactions=500
SharedGlobalMemory=500K
LongMessageBuffer=512K
MaxParallelScansPerFragment=16
MaxNoOfAttributes=100
MaxNoOfTables=20
MaxNoOfOrderedIndexes=20

[ndbd]
hostname=192.168.1.122
datadir=/home/pi/mysql/ndb_data
NodeId=3

[ndbd]
hostname=192.168.1.118
datadir=/home/billy/my_cluster/ndbd_data
NodeId=4

[mysqld]
NodeId=50

[mysqld]
NodeId=51

[mysqld]
NodeId=52

[mysqld]
NodeId=53

[mysqld]
NodeId=54

Running the management node worked pretty easily but then I had problems starting the data nodes – checking how much memory I had available gave me a hint as to why!

pi@raspberrypi:~$ free -m
             total       used       free     shared    buffers     cached
Mem:           186         29        157          0          1         11
-/+ buffers/cache:         16        169
Swap:            0          0          0

OK – so 157 Mbytes of memory available and no swap space, not ideal and so the next step was to use gparted again to create swap partitions on the SD card as well a massive 1Gbyte on my MySQL branded USB stick (need to persuade marketing to be a bit more generous with those). A quick edit of /etc/fstab and a restart and things were looking in better shape:

pi@raspberrypi:~$ free -m
             total       used       free     shared    buffers     cached
Mem:           186         29        157          0          1         11
-/+ buffers/cache:         16        169
Swap:         1981          0       1981

Next to start up the management node and 1 data node on the Pi as well as a second data node on the Linux server “ws2″ (I want High Availability after all – OK so running the management node on the same host as a data node is a single point of failure)…

pi@raspberrypi:~/mysql$ ndb_mgmd -f conf/config.ini --configdir=/home/pi/mysql/conf/ --initial
pi@raspberrypi:~/mysql$ ndbd
billy@ws2:~$ ndbd -c 192.168.1.122:1186

I could then confirm that everything was up and running:

pi@raspberrypi:~$ ndb_mgm -e show
Connected to Management Server at: localhost:1186
Cluster Configuration
---------------------
[ndbd(NDB)]     2 node(s)
id=3    @192.168.1.122  (mysql-5.5.22 ndb-7.2.6, Nodegroup: 0, Master)
id=4    @192.168.1.118  (mysql-5.5.22 ndb-7.2.6, Nodegroup: 0)

[ndb_mgmd(MGM)] 1 node(s)
id=1    @192.168.1.122  (mysql-5.5.22 ndb-7.2.6)

[mysqld(API)]   5 node(s)
id=50 (not connected, accepting connect from any host)
id=51 (not connected, accepting connect from any host)
id=52 (not connected, accepting connect from any host)
id=53 (not connected, accepting connect from any host)
id=54 (not connected, accepting connect from any host)

Cool!

Next step is to run a MySQL Server so that I can actually test the Cluster – if I tried running that on the Pi then it caused problems (157 Mbytes of RAM doesn’t stretch as far as it used to) – on ws2:

billy@ws2:~/my_cluster$ cat conf/my.cnf
[mysqld]
ndbcluster
datadir=/home/billy/my_cluster/mysqld_data
ndb-connectstring=192.168.1.122:1186

billy@ws2:~/my_cluster$ mysqld --defaults-file=conf/my.cnf&

Check that it really has connected to the Cluster:

pi@raspberrypi:~/mysql$ ndb_mgm -e show
Connected to Management Server at: localhost:1186
Cluster Configuration
---------------------
[ndbd(NDB)]     2 node(s)
id=3    @192.168.1.122  (mysql-5.5.22 ndb-7.2.6, Nodegroup: 0, Master)
id=4    @192.168.1.118  (mysql-5.5.22 ndb-7.2.6, Nodegroup: 0)

[ndb_mgmd(MGM)] 1 node(s)
id=1    @192.168.1.122  (mysql-5.5.22 ndb-7.2.6)

[mysqld(API)]   5 node(s)
id=50   @192.168.1.118  (mysql-5.5.22 ndb-7.2.6)
id=51 (not connected, accepting connect from any host)
id=52 (not connected, accepting connect from any host)
id=53 (not connected, accepting connect from any host)
id=54 (not connected, accepting connect from any host)

Finally, just need to check that I can read and write data…

billy@ws2:~/my_cluster$ mysql -h 127.0.0.1 -P3306 -u root
mysql> CREATE DATABASE clusterdb;USE clusterdb;
Query OK, 1 row affected (0.24 sec)

Database changed
mysql> CREATE TABLE simples (id INT NOT NULL PRIMARY KEY) engine=ndb;
120601 13:30:20 [Note] NDB Binlog: CREATE TABLE Event: REPL$clusterdb/simples
Query OK, 0 rows affected (10.13 sec)

mysql> INSERT INTO simples VALUES (1),(2),(3),(4);
Query OK, 4 rows affected (0.04 sec)
Records: 4  Duplicates: 0  Warnings: 0

mysql> SELECT * FROM simples;
+----+
| id |
+----+
|  1 |
|  2 |
|  4 |
|  3 |
+----+
4 rows in set (0.09 sec)

OK – so is there any real application to this? Well, probably not other than providing a cheap development environment – imagine scaling out to 48 data nodes, that would cost $1,680 (+ the cost of some SD cards)! More practically might be management nodes – we know that they need very few resources. As a reminder – this is not a supported platform!

MySQL Cluster Manager 1.1.6 released

MySQL Cluster Manager 1.1.6 is now available to download from My Oracle Support.

Details on the changes can will be added to the MySQL Cluster Manager documentation . Please give it a try and let me know what you think.

Note that if you’re not a commercial user then you can still download MySQL Cluster Manager 1.1.5 from the Oracle Software Delivery Cloud and try it out for free. Documentation is available here.

MySQL Cluster 7.1.22 is available for download

The binary version for MySQL Cluster 7.1,21 has now been made available at https://www.mysql.com/downloads/cluster/7.1.html#downloads (GPL version) or https://support.oracle.com/ (commercial version).

A description of all of the changes (fixes) that have gone into MySQL Cluster 7.1.22 (compared to 7.1.21) are available from the 7.1.22 Change log.

MySQL Cluster 7.2.6 is available for download

The binary version for MySQL Cluster 7.2.6 has now been made available at http://www.mysql.com/downloads/cluster/ (GPL version) or https://support.oracle.com/ (commercial version).

A description of all of the changes (fixes) that have gone into MySQL Cluster 7.2.6 (compared to 7.2.5) are available from the 7.2.6 Change log.

Upcoming conferences to learn more about MySQL Cluster & Replication

There are a couple of conferences coming up where you can expect to learn about the latest developments in MySQL Cluster and MySQL Replication (as well as what else is happening in MySQL 5.6).

The first is the Oracle MySQL Innovation Day which is being held in Oracle HQ at Redwood Shores. This is an all-day event on 5th June – unfortunately I won’t be able to attend this one but there will be lots of great Cluster and replication sessions. If you can’t make it out to California then there will be a live Webcast. You can register here to attend in person or join the webcast.

The second is MySQL Connect – this runs the weekend before Oracle OpenWorld in San Francisco; it’s not  until 29th September but it’s worth registering now to get the early bird pricing and save $500 (end 13th July). There are lots of great sessions lined up both from the MySQL experts within Oracle and users and community members.