Use table extension

This example shows you how to set the Table Extension parameter to a table rotation group.

Before you begin

Role required: admin

About this task

Note:

Deploy this plugin in partnership with a ServiceNow representative.

Administrators typically specify the time parameter (duration) of the process, but may alternatively specify the number of tables (rotations). After the last table in a rotation is written, new tables are added and old tables are archived. Using table extension, tables are never overwritten.

An advantage of table extension is to partition data across tables. It also allows you to archive data while ensuring that tables stay reasonably-sized. The working set of data is reduced when a date is known for the query.

The disadvantage is that table extension requires a union query when you query for a time range that spans multiple tables. Union queries are less efficient than queries against a single table.

A good practice is to use table extension when you have sequentially-written tables or insert-only type tables (there are exceptions to this parameter). Table extension is also useful in tables where data is needed for long periods of time.

The following example describes how to set table extension for a custom table.

Procedure

1. Navigate to All > System Definition > Table Rotations.
2. Click New.
3. Enter the following information.

   Field	Action
   Name	Enter the name of the table to apply the action.
   Duration	Enter the overall duration for the action. 30 days is the duration in this example.
   Type	Select Extension.

4. Click Submit.