Sybase DC38133-01-0902-01 manual Log entries are values, not subscribers

Chapter 8. SQL Remote Design for Adaptive Server Enterprise

Log entries are values, not subscribers

Although in this case the values entered correspond to subscribers, it is not a list of subscribers that is entered in the log. The server handles only information about publications, and the Message Agent handles all information about subscribers. The values entered in the log are for comparison to the subscription value in each subscription. For example, if rows of a table were divided among sales representatives by state or province, the state or province value would be entered in the transaction log.

A subscription-list column is a column added to a table for the sole purpose of holding a comma-separated list of subscribers. In the present case, there can only be a single subscriber to each row of the Contact table, and so the subscription-list column holds only a single value.

☞For a discussion of the case where the subscription-list column can hold many values, see “Sharing rows among several subscriptions” on page 157 .

Contact table definition In the case of the Contact table, the table definition would be changed to the following:

CREATE TABLE Contact ( contact_key CHAR( 12 ) NOT NULL, name CHAR( 40 ) NOT NULL, cust_key CHAR( 12 ) NOT NULL, subscription_list CHAR( 12 ) NULL, FOREIGN KEY ( cust_key ) REFERENCES Customer ( cust_key ), PRIMARY KEY ( contact_key )

)

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The additional column is created allowing NULL, so that existing applications can continue to work against the database without change.

The subscription_list column holds the rep_key value corresponding to the row with primary key value cust_key in the Customer table. A set of triggers handles maintenance of the subscription_list column.

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