Default read/write queries in TileDB are synchronous or blocking. This means that the user function that is submitting the query has to block and wait until TileDB is done processing the query. There are scenarios in which you may want to submit the query in an asynchronous or non-blocking fashion. In other words, you may wish to submit the query but tell TileDB to process it in the background, while you proceed with the execution of your function and perform other tasks while TileDB is executing the query in parallel. TileDB supports asynchronous queries and enables you to check the query status (e.g., if it is still in progress). It also allows to pass a callback upon submission, i.e., specify a function that you wish TileDB to compute upon finishing processing the query. This applies to both dense and sparse arrays, as well as to both write and read queries.
The figure below shows the difference between synchronous and asynchronous query execution.
TileDB allocates a separate thread pool for asynchronous queries, whose size is controlled by configuration parameter
sm.num_async_threads (defaulting to 1).