Asynchronous query. The search call return immediately and result delievered as a signal later. The actual query is done in a separate thread.
If the database is busy scanning, then the query is performed later when database is ready. It returns NULL and result is delivered through async-result signal. Only query can stay queued, so calling search multiple times would result in only the last one being active.
Syncronous query. The result is immediately available as retrun value of search call.
This parameter determines the mode of query execution. By default, IANJUTA_SYMBOL_QUERY_MODE_SYNC is selected.