Re: [HACKERS] Safe/Fast I/O ...

> As David Gould mentioned, we need to do pre-fetching of data pages
> somehow.
> 
> When doing a sequential scan on a table, the OS is doing a one-page
> prefetch, which is probably enough.  The problem is index scans of the
> table.  Those are not sequential in the main heap table (unless it is
> clustered on the index), so a prefetch would help here a lot.
> 
> That is where we need async i/o.  I am looking in BSDI, and I don't see
> any way to do async i/o.  The only way I can think of doing it is via
> threads.

I found it.  It is an fcntl option.  From man fcntl:

     O_ASYNC      Enable the SIGIO signal to be sent to the process group when
                  I/O is possible, e.g., upon availability of data to be read.

Who else supports this?

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