Extension Index are nothing but secondary indexes for the SAP standard tables.When you create a secondary index in normal way, SAP considers its as a modification to the table. But when you create an Extension index, we are not actually modifying the standard table, we are enhancing it. This concept is also introduced in new Enhancement framework netweaver version 7.0
What are the drawbacks with the normal Secondary Index creation ?
Even though you have created the secondary index in customer namespace, these will not be available when you upgraded the system with new releases. We have to again create the secondary index after completing the upgrade activities.
What benefits we get with Extension Index ?
These indexes are upgrade protected. We can still able to see these indexes after system upgrade.
Lets see how we can create the Extension Index for standard tables. In this tutorial i will create Extension Index a.k.a secondary index for standard table VBAP.
1. Go to SE11-Dictionary MaintenanceABAP, select VBAP table and click on “Indexes”.
2. You will see a popup screen like below and in the same screen click on create button and choose Extension Index.
3. Enter the Index Name in next screen and click on OK button.
4. Enter the Short Description and choose the field name on which you want to create a secondary index for the table.In this example i have selected MATNR field for creating secondary index.
5. Activate the index by providing the package name in which you want to save the index.
Now you have successfully created the secondary index which is upgrade protected.