Snapshot replication:
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Thread: Snapshot replication:

  1. #1
    Join Date
    Jan 2001
    Posts
    642

    Snapshot replication:

    Hi,

    In a updateable snapshot replication, when only one column is updated on the master, will the entire record be updated on the replicated site or only the column on which the changes happened will get replicated.

    Eg: col2 changes(updated) on the master table log.(There are 4 col: Col1,col2,col3,col4).
    When the refresh process happens,

    Will the oracle refresh the entire row (all the columns) or only the col2 is sent to the replication site:

    We need to change the logic of one of the batch programs based on this input.

    Please let me know.
    Thanks,
    Badrinath
    There is always a better way to do the things.

  2. #2
    Join Date
    Apr 2001
    Location
    Brisbane, Queensland, Australia
    Posts
    1,203
    Well, if you are updating the Master Site, that isn't utilising UPDATEABLE snapshot functionality really. Updating the master occurs on any type of snapshot, I think you are asking: Does a SNAPSHOT REFRESH ONLY the modify the changed column at the snapshot site, or ALL colomns for an updated record.... hmmm, good question.

    I'm about 70% sure that Oracle only carries over the modified value, and I even discussed this with a collegue and he agreed. Nevertheless, that just our opinion, I'd like to find some harder evidence for you, I'll snoop around...

    Internal Trigger for the Materialized View Log

    When changes are made to the master table or master materialized view using DML, an internal trigger records information about the affected rows in the materialized view log. This information includes the values of the primary key, rowid, or object id, or both, as well as the values of the other columns logged in the materialized view log. This is an internal AFTER ROW trigger that is automatically activated when you create a materialized view log for the target master table or master materialized view. It inserts a row into the materialized view log whenever an INSERT, UPDATE, or DELETE statement modifies the table's data. This trigger is always the last trigger to fire.

    This STILL doesn't clarify the issue though... sorry.
    Last edited by grjohnson; 03-26-2003 at 02:04 AM.
    OCP 8i, 9i DBA
    Brisbane Australia

  3. #3
    Join Date
    Apr 2002
    Location
    Bangalore
    Posts
    47

    Re: Snapshot replication:

    Originally posted by badrinathn
    Hi,


    Eg: col2 changes(updated) on the master table log.(There are 4 col: Col1,col2,col3,col4).
    When the refresh process happens,

    Will the oracle refresh the entire row (all the columns) or only the col2 is sent to the replication site:

    Hi i don't have any docs to support .but i belive the entire row is refreshed.
    Cheers
    Murali

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