class async_exec :'mode async_connection -> Unixqueue.event_system -> ?expect:Postgresql.result_status list -> ?params:string array -> ?binary_params:bool array -> ?copy_in_lines:string list -> ?noprepare:bool -> string ->[Postgresql.result]Uq_engines.engine
The query is sent immediately. The response is awaited in an
asynchronous way. When it is complete, the engine transitions
to state `Done r where r is the result. In case of an error,
the engine transitions to `Error e where e is the exception.
copy_in_lines is for "COPY IN" statements. noprepare does not
prepare the statement (useful if it is not constant).
An abort invocation cancels the current query.
