Options for including unchanged columns in messages for publications

When you create publications that publish a subset of the source columns, you can specify what column values from each row the Q Capture program includes in the message that it publishes.

The following sections describe the values that the Q Capture program can include in the message: This option applies only to values in non-key columns. The Q Capture program always publishes values in key columns.

Only changed columns are sent

By default when you create publications, the Q Capture program sends the values in the columns that you selected for the publications only if the column values change.

Example: Assume that you have 100 columns in your source table and you select 25 of those columns to be published in a publication. If you specify that only changed columns are sent, then any time that a change occurs in any of the 25 selected columns, the Q Capture program publishes only the columns that changed. For instance, if changes occur in 17 of the 25 selected columns, then the Q Capture program sends those 17 changed values.

Recommendation: Use this option to minimize the amount of unnecessary data that goes across the queues.

Both changed and unchanged columns are sent

You can also define publications so that the Q Capture program always sends the values in the columns that you selected for the publications, whether those values changed or not.

Example: Assume that you have 100 columns in your source table and you select 25 of those columns to be published in a publication. If you specify that both changed and unchanged columns are sent, then any time that a change occurs in any of the 25 selected columns, the Q Capture program publishes all of the selected columns. For instance, if changes occur in 17 of the 25 selected columns, then the Q Capture program still sends the values from all 25 columns.