I have some table :

create table people
    id             bigint        not null    default autoincrement,
    first_name     varchar(50)   not null,
    last_name      varchar(50)   not null,
    gender         char(1)       not null    default 'M', 
    last_update    timestamp     not null    default timestamp  

What happens in a replicating environment if remote user 1 updates a row, and then replicates the change to the main site? Does the last_update get updated AGAIN at the main site when the change arrives and is processed?

Please tell me it doesn't.

asked 27 Jan '10, 18:35

Calvin%20Allen's gravatar image

Calvin Allen
accept rate: 25%

edited 27 Jan '10, 19:39

Your example is somewhat lacking a "real" column: You wouldn't want to update the id (as a PK field) in a SQL Remote setup, otherwise last_update wouldn't be the problem:)

(27 Jan '10, 18:48) Volker Barth

Example updated.

(27 Jan '10, 19:40) Calvin Allen


it doesn't.

When you look at the SQL statements that are sent to the other side (by running DBREMOTE -v -o C:\┬┤MyLog.txt) you will notice that the receiving database gets a complete statement with the *last_update* column set. And the particular DEFAULT TIMESTAMP default will only be applied when the column's value is not set explicetely. So no need to worry, we have used this DEFAULT in a SQL Remote setup for years.

As to your new example: If the remote exeucutes the following SQL statement (say, in a client app):

UPDATE people SET last_name = 'Smith' WHERE id = 123450000

then last_update will be set automatically to current timestamp (say, to '2010-01-28 11:24:23.123456'). The transaction log will then contain something like (you could check by using DBTRAN):

UPDATE people SET last_name = 'Smith', last_update = '2010-01-28 11:24:23.123456'  WHERE id = 123450000

And it's that statement that is sent to the consolidated. Obviously, the statement contains a value for the DEFAULT TIMESTAMP column, so it doesn't update *last_update* again.

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answered 27 Jan '10, 18:45

Volker%20Barth's gravatar image

Volker Barth
accept rate: 32%

edited 28 Jan '10, 10:03

Awesome, thanks! We're just looking to implement this default and had concerns of the affects replication might bring.

(27 Jan '10, 18:48) Calvin Allen

Just to add: We have included 3 columns in all published tables: one "dtCreated" with DEFAULT CURRENT TIMESTAMP. one "dtLastUpdated" with DEFAULT TIMESTAMP and one "origin" with DEFAULT CURRENT PUBLISHER. That makes tracking the source of inserts/updates quite easy.

(28 Jan '10, 10:06) Volker Barth
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question asked: 27 Jan '10, 18:35

question was seen: 937 times

last updated: 28 Jan '10, 10:03