When do Azure SQL Database index rebuilds occur?
When do index rebuilds occur in Azure SQL? Are they automatic or manually selected in a maintenance window?


The index rebuilds, at the time of writing the answer, in SQL Server is not automatic, I hope you are not mixing it with automatic index tuning. There is no "SQL Server agent" in Azure SQL database you have the option to schedule jobs via Elastic Job Agent to run Ola Hallengren Index maintenance job for index rebuild/reorganize and stats update, you can also use your personal index maintenance script. Please note Elastic Job agent is still in preview and requires the Azure SQL database to be on size S0 and above. Read more about Database elastic jobs

You also have option to create Azure automation account for job scheduling