Asynchronous database index maintenance

This disclosure provides techniques for asynchronously maintaining database indexes or sub-indexes. For example, a database management server may receive a data manipulation statement to modify particular data stored in a database and determine whether an index associated with executing the statement is maintained asynchronously. When the index is maintained asynchronously, maintenance of the index to reflect changes made to the particular data by executing the data manipulation statement may be delayed until an index maintenance event. The index maintenance may be based on an isolation level of a transaction including a query that triggered the index maintenance.