1. A method of building a search index for a database, the method comprising: detecting an incremental build trigger; determining that a first sub-index is to be updated, the first sub-index being in a plurality of sub-indexes that make up the search index; determining that a second sub-index is not to be updated, the second sub-index being in the plurality of sub-indexes that make up the search index; generating a third sub-index based on the first sub-index and an index update; executing a first query using the first sub-index , the second sub-index, and not the third sub-index during generation of the third sub-index; and executing a second query using the second sub-index, the third sub-index, and not the first sub-index after generation of the third sub-index.