I have a MySQL database with some data in it. Now I want to create cluster from this this database.
I've already configured Galera, and I have just this single node. Now, how to replicate the data to ather nodes?
Will it happen auto-maicaly by Galera, or should I dump current data first, then clean the DB on the first node, start all other nodes and load the data to one of them and wait for them to replicate.
Following question is: how to add/remove nodes in runtime?
Just if somebody is still interested in an answer to this.
The procedure is:
bootstrap the cluster by starting the first node
add other nodes as needed
Any new nodes will first receive the current state of the DB before becoming available.
https://mariadb.com/kb/en/mariadb/getting-started-with-mariadb-galera-cluster/#getting-started
Related
I just used mySQL workbench to connect to my clearDB account which is connected to an azure web app. The problem is even thought I ran a query that drops/creates tables in the newly made schema that mirrors exactly the tables and data in my previous live server, I go to mysite.azurewebsites.com/wp-admin and the error is in establishing data connection. Site could not be found. Check if your database contains the following pages: wp_blogs, ..........
What could be the problem? Does this process just need a bit of time to propagate all the data?
EDIT: something to note, which might be a factor, when I ran the last query, it also included dropping/adding the table "wp_users" so all previous data was wiped and replaced with the info from a previous live server.
Normally you will see any changes made immediately. But because your database is hosted on a geoseparated cluster in circular replication there are some rare circumstances where this might not be true.
Specifically, if your delete/write went to one master and your read query went to another. Data propagation is normally immediate but if one of the nodes is offline or the system is unusually busy there can be a delay.
I have task to implement particular database structure:
Multiple mysql servers with data using the same schema. Each server can see and edit only his particular part of data.
And
One master server with his own data that can run queries using data from all previously mentioned servers, but cannot edit them.
Example would be multiple hospitals with data of their patients and master server that can use combined data from all hospitals.
Previous system was written using mysql cluster, so i tried it naturally. I can create mysql cluster with multiple nodes and maybe even partition data so i can have particular set of data in particular node, but as far as i know i can't connect to single node using mysql, because it is already connected to cluster.
Can it be done with mysql cluster? Is there other framework that can do that easily?
You could try to use http://galeracluster.com/. You can perform updates on all slaves and every server has all data, but it might still meet your requirements.
Im new to clustering and Im doing a project on cluster database. I want to make use of MySQL Cluster. Im using it for a small scale database and this is my plan:
5 node:
1 management node,
2 SQL node,
2 API node.
My questions are:
1) Is my plan for the node process alright?
2) What should I do when I got the error "Failed to allocate node id..."?
3) Is it a requirement to use multi-threaded data node?
4) Where do I place my web server page for the user to access the database?
Please reply. Thank you so much.
This answer might be a little late but can be helpful for someone else getting started:
1) Is my plan for the node process alright?
Your plan for the node process is ok for a small cluster. I would recommend adding an additional management node and 2 more Data Nodes if the number of replicas you have configured is 2. Reason being since you currently have only 2 data nodes, your cluster will not be functionally should once of those nodes "die" . This is because of the two-phase commit that takes place. In the case of a faiure only 1 data node will be able to persist the data , the other one would be unreachable and therefore the transaction would be marked as incomplete.
2) What should I do when I got the error "Failed to allocate node
id..."?
This error is usually thrown if you have assigned the same id to other nodes in your configuration file. Each node should have a unique Id.
3) Is it a requirement to use multi-threaded data node?
It is not a requirement but recommended. Using mulch-threaded data node allows you to leverage modern computer architecture with multiply cpus to allow for your data processing queries to be processed much faster. As a result updates and queries will be done much faster
4) Where do I place my web server page for the user to access the
database?
Hmm.Not sure why you want to achieve here. This would be a separate question, if you are using PHP or usually any other language. You will have to have a web server configured. Place them in the root of the http directory to get started
So what's the idea behind a cluster?
You have multiple machines with the same copy of the DB where you spread the read/write? Is this correct?
How does this idea work? When I make a select query the cluster analyzes which server has less read/writes and points my query to that server?
When you should start using a cluster, I know this is a tricky question, but mabe someone can give me an example like, 1 million visits and a 100 million rows DB.
1) Correct. Every data node does not hold a full copy of the cluster data, but every single bit of data is stored on at least two nodes.
2) Essentially correct. MySQL Cluster supports distributed transactions.
3) When vertical scaling is not possible anymore, and replication becomes impractical :)
As promised, some recommended readings:
Setting Up Multi-Master Circular Replication with MySQL (simple tutorial)
Circular Replication in MySQL (higher-level warnings about conflicts)
MySQL Cluster Multi-Computer How-To (step-by-step tutorial, it assumes multiple physical machines, but you can run your test with all processes running on the same machine by following these instructions)
The MySQL Performance Blog is a reference in this field
1->your 1st point is correct in a way.But i think if multiple machines would share the same data it would be replication instead of clustering.
In clustering the data is divided among the various machines and there is horizontal partitioning means the dividing of the data is based on the rows,the records are divided by using some algorithm among those machines.
the dividing of data is done in such a way that each record will get a unique key just as in case of a key-value pair and each machine also has a unique machine_id related which is used to define which key value pair would go to which machine.
we call each machine a cluster and each cluster consists of an individual mysql-server, individual data and a cluster manager.and also there is a data sharing between all the cluster nodes so that all the data is available to the every node at any time.
the retrieval of data is done through memcached devices/servers for fast retrieval and
there is also a replication server for a particular cluster to save the data.
2->yes, there is a possibility because there is a sharing of all the data among all the cluster nodes. and also you can use a load balancer to balance the load.But the idea of load balancer is quiet common because they are being used by most of the servers. but if you are trying you just for your knowledge then there is no need because you will not get to notice the type of load that creates the requirement of a load balancer the cluster manager itself can do the whole thing.
3->RandomSeed is right. you do feel the need of a cluster when your replication becomes impractical means if you are using the master server for writes and slave for reads then at some time when the traffic becomes huge such that the sever would not be able to work smoothly then you will feel the need of clustering. simply to speed up the whole process.
this is not the only case, this is just one of the scenario this is only just a case.
hope this is helpful for you!!
I have a small hadoop/hive cluster (6 nodes in total).
Using "hadoop dfsadmin -report" I see that are datanodes are working well and connected.
Additionally when I add data in a hive table I can see that the data are being distributed
all over the node. (Easy to check, as the disk space used increases).
I am trying to create some indexes on one table. From the jobtracker http interface, I see only one node available. I tried to run multiple queries ( I use mysql for the metadata) but they appear to run only on the node that hive is installed.
Basically My question is how to make the jobtracker to utilize the other nodes as well.
From what you tell it looks that:
Datanodes are properly running on all nodes and able to communicate with namenode.
Task trackers are not running on all nodes except of one, or, are not able to communicate with the job tracker for some reason.
After checking that task trackers indeed running - read their logs to find out what is their problem to communicate with JobTracker.