Best Practices to update/add/remove fields for an Azure Search Index

Question

I was wondering if there any good resources for best practices to deal with changes (Add/remove fields from search index) to your search index without taking your Azure search service and index down. Do we need to create a completely new index and indexer to do that? I discovered that the Azure portal currently lets you add new fields to your index but what about updating/deleting fields from your search index.

Thanks!

Answer 1

If you add a field there is no strict requirement on rebuild. Existing indexed documents are given a null value for the new field. On a future re-index, values from source data are added to documents.

While you can't directly delete a field from an Azure Search index, you can achieve the same effect without rebuilding the index by having your application simply ignore the "deleted" field. If you use this approach, a deleted field isn't used, but physically the field definition and contents remain in the index until the next time you rebuild your index.

Changing a field definition requires you to rebuild your index, with the exception of changing these index attributes: Retrievable, SearchAnalyzer, SynonymMaps. You can add the Retrievable, SearchAnalyzer, and SynonymMaps attributes to an existing field or change their values without having to rebuild the index.