User's Manual

Chapter 7. SQL Remote Design for Adaptive Server Anywhere
♦ The following is a single-article publication sending relevant order
information to Samuel Singer, a sales rep:
CREATE PUBLICATION pub_orders_samuel_singer (
TABLE sales_order WHERE sales_rep = 856
)
☞ For more information, see the “CREATE PUBLICATION statement”
[ASA SQL Reference, page 385].
SUBSCRIBE BY
The create publication statement also allows a SUBSCRIBE BY clause.
This clause can also be used to selectively publish rows in SQL Remote.
However, it is ignored during MobiLink synchronization.
Publishing only some rows using a subscription expression
You can specify a subscription expression to include a different set of rows
in different subscriptions to publications containing the article.
For example, in a mobile workforce situation, a sales publication may be
wanted where each sales rep subscribes to their own sales orders, enabling
them to update their sales orders locally and replicate the sales to the
consolidated database.
Using the WHERE clause model, a separate publication for each sales rep
would be needed: the following publication is for sales rep Samuel Singer:
each of the other sales reps would need a similar publication.
CREATE PUBLICATION pub_orders_samuel_singer (
TABLE sales_order
WHERE sales_rep = 856
)
To address the needs of setups requiring large numbers of different
subscriptions, SQL Remote allows a subscription expression to be
associated with an article. Subscriptions receive rows depending on the
value of a supplied expression.
Benefits of subscription
expressions
Publications using a subscription expression are more compact, easier to
understand, and provide better performance than maintaining several
WHERE clause publications. The database server must add information to
the transaction log, and scan the transaction log to send messages, in direct
proportion to the number of publications. The subscription expression
allows many different subscriptions to be associated with a single
publication, whereas the WHERE clause does not.
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