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Thread: Replication

  1. #1
    Join Date
    Jan 2001
    Posts
    216
    Hi,

    In Master-Master replication, I am setting up a delay time after which all the changes to Master1 will be purged and applied to Master2. Is there a way by which we can update both Masters in one transaction ? If there is, is that approach recommended ?

    Thanks

  2. #2
    Join Date
    Nov 2000
    Posts
    212
    if one of masters is not available, what should happen then?

  3. #3
    Join Date
    Dec 2000
    Posts
    43
    First of all, why would you want to do that if you are replicating and what type of transaction would it be?
    Secondly, if you require to do this, there are some conflict resolution methods you can use to set priorities etc.

  4. #4
    Join Date
    May 2000
    Location
    ATLANTA, GA, USA
    Posts
    3,135
    Is your replication ACTIVE-ACTIVE or ACTIVE-PASSIVE?

  5. #5
    Join Date
    Jan 2001
    Posts
    216
    The replication we have is active-active. The transaction I was referring could be any insert, update or delete.
    We want to keep both the masters in sync as we will be using them to implement TAF, so if one database dies the user must not have access to stale data if the other picks up before the changes were updated.. I guess I must do more research on conflict resolution methods.

    Where can I find good documentation on conflict resolution methods ?

    Thanks for your answers

  6. #6
    Join Date
    Dec 2000
    Posts
    43
    I have a pdf that I can send you if you provide an email address.
    Also look in the Help documentation for Oracle Advanced Replication. They have conflict resolution in detail.

  7. #7
    Join Date
    Jan 2001
    Posts
    216
    Thanks

    my email address is : chikkodi@hotmail.com

  8. #8
    Join Date
    Nov 2000
    Posts
    212
    Oops, it seems you need very much really. Am I right:

    status0: table T has 1 record with colum C=0
    server1: update T set C=1
    server1: dies
    server2: user continues on server2, but here coms problem:
    T has 1 record with column C=0, while application assumes it is C=1 and continues with that assumtion, for example, commits?

    If so, you need synchronous replication, but such, that DB is not stalled if one of servers is not available. Synchronous replication is simple: just Db triggers. What is not simple, how to queue changes on server2 while server 1 is not available?

    Probably you really have to rely on queue provided by multimaster replication and JUST use conflict resolution to discard changes done by synchronous replication (Db triggers). In general it seems very complicated... Standby DB is better alternative then.




  9. #9
    Join Date
    Dec 2000
    Posts
    43
    I tried to send the .pdf file but hotmail exceeded the size.
    I think if you look at the online help for conflict resolution, it will be helpful to you. Good Luck!

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