This discussion is archived
1 Reply Latest reply: Jan 13, 2012 6:46 AM by Charles Lamb RSS

General understand of Oracle NoSQL

896774 Newbie
Currently Being Moderated
Hi all,

Please can help me understand the following:
1) How master is initially designated? Using PAXOS algorithm or chosen by administrator during install?
2) Can one node change from master to replica? In which cases? Is it only due to network partition ?
3) How many versions of records are maintained in storage nodes? Is that number configurable?
4) From your point of view, is Oracle NoSQL CP? AP? Or even CA? In which case, can’t Oracle NoSQL meet Partition tolerance requirement? With the example when master is in minority partition ?
Thanks.
  • 1. Re: General understand of Oracle NoSQL
    Charles Lamb Pro
    Currently Being Moderated
    893771 wrote:
    Please can help me understand the following:
    1) How master is initially designated? Using PAXOS algorithm or chosen by administrator during install?
    When the nodes in a Rep Group come up, they elect a master. The algorithm and protocol is PAXOS, but the election of a master is based on which node is most up-to-date. Presently, there is no way to choose which node is master during the install, but this is something we are working on for a future release. We are well-aware that this capability is needed.
    2) Can one node change from master to replica? In which cases? Is it only due to network partition ?
    In general, any node can be elected as a master. Failure of the master is a good reason for an election to be held among the remaining replicas. A network partition is not required for an election to be held.
    3) How many versions of records are maintained in storage nodes? Is that number configurable?
    1. No.
    4) From your point of view, is Oracle NoSQL CP? AP? Or even CA? In which case, can’t Oracle NoSQL meet Partition tolerance requirement? With the example when master is in minority partition ?
    The answer to this question is complicated, but I will offer you the following food for thought and leave the answer as an exercise to the reader:

    We recommend that the system be configured to always use at least simple majority replica ack policy.

    Charles Lamb

Legend

  • Correct Answers - 10 points
  • Helpful Answers - 5 points