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Displaying posts with tag: message-passing (reset)

Reports exaggerated
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I've been letting the blog rest recently, and not so recently as well.  The problem is not a lack of subjects, but a lack of time to do them any justice.  However it is quite sad to see that my last entry was in September 2012, so it is time to post again.

Of late I have been pondering what I have to say about :

  • Distributed MVCC and write-scaling
  • Different approaches to eventual consistency with replicated RDBMS
  • Various MySQL Cluster related topics
  • Various general rambling and unstructured topics

However, these will take some time to percolate and calcify. …




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The CAP theorem and MySQL Cluster
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tldr; A single MySQL Cluster prioritises Consistency in Network partition events. Asynchronously replicating MySQL Clusters prioritise Availability in Network partition events.

I was recently asked about the relationship between MySQL Cluster and the CAP theorem. The CAP theorem is often described as a pick two out of three problem, such as choosing from good, cheap, fast. You can have any two, but you can't have all three. For CAP the three qualities are 'Consistency', 'Availability' and 'Partition tolerance'. CAP states that in a system with data replicated over a …

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Data distribution in MySQL Cluster
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MySQL Cluster distributes rows amongst the data nodes in a cluster, and also provides data replication. How does this work? What are the trade offs?

Table fragments

Tables are 'horizontally fragmented' into table fragments each containing a disjoint subset of the rows of the table. The union of rows in all table fragments is the set of rows in the table. Rows are always identified by their primary key. Tables with no primary key are given a hidden primary key by MySQLD.

By default, one table fragment is created for each data node in the cluster at the time the table is created.

Node …







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Ndb software architecture
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I'm sure that someone else can describe the actual history of Ndb development much better, but here's my limited and vague understanding.

  • Ndb is developed in an environment (Ericsson AXE telecoms switch) where Ericsson's PLEX is the language of choice
    PLEX supports multiple state machines (known as blocks) sending messages (known as signals) between them with some system-level conventions for starting up, restart and message classes. Blocks …


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Showing entries 1 to 4

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