Most known practice to speed up searches on the standard tables is to create secondary indexes. SAP has introduced a new enhancement technique called Extension index as part of Enhancement Framework. It is same as creating secondary index for the standard table.
SAP has already delivered secondary indexes for most of the standard table. It is not necessary that the existing secondary index fulfill all scenarios. In such cases, creating a secondary index on a standard table comes under modification. During upgrade, they will be deleted and need to be re-created in a system. This involves efforts and cost. Extension indexes are automatically copied over during upgrades and no modification adjustment takes place.
How to create
1. Go to SE11-> Enter table name-> click on Indexes-> Create Extension Index
2. System will display screen same as ‘Creating Secondary Index’. Enter the required data.
3. Save and activate it. Assign a package and transport request for the extension index.