Build Index: Incremental updates an index in what scenario?

• A. Creates a new index from existing data.
• B. Deactivates the index in the search menu.
• C. Updates an index after adding or removing documents.
• D. Swaps the index with a replacement index.

Answer: (C)

Incremental updates are used to keep the index in sync with changes to the document collection. When you add or remove documents, the index must reflect those changes so search results remain accurate. Instead of rebuilding the whole index from scratch, an incremental update modifies the existing index: it adds new postings for newly added terms, updates term frequencies and positions as needed, and removes postings for deleted documents. This approach maintains up-to-date searchability with much less overhead than a full rebuild.

Creating a new index from existing data would be a full rebuild, which is more resource-intensive and unnecessary for small changes. Deactivating the index doesn’t update it at all. Swapping the index with a replacement index changes which index is used, not the process of updating the current one to reflect document changes.