Re: Async I/O

> I'm sure you've probably thought about this (and discarded it for
> a variety of reasons), but here it goes anyway:
>
> Have some daemon ("postmaster" itself, perhaps) service requests for
> pages asynchronously. For example, have each "postgres" client request
> the pages from "postmaster" and continue running; "postmaster" could
> service the request, map the resulting pages into the shared segment, and
> notify the appropriate "postgres" client (either through the socket
> or some other way) asynchronously. The "postgres" client could then
> be checking the socket with a non-blocking select whenever it wanted to.
> (Or you could notify the client with a signal telling it that the request
> has been serviced and it can go and get the pages.)
>
> It's just a suggestion. Good luck and congratulations for the excellent
> work you've done with postgresql.
>
> -Ted.
>
> p.s. I've got a table that's 77 MB (340,000 records), with six indexes on
> it totaling another 66 MB. It does pretty well, actually.

Above is a very good review of a platform-independent way for us to do
async read-aheads, particularly for heap reads from indexes. I think it
deserves consideration as a good way to perform what we need done.

Shared memory certainly gives us a way to communicate between these
processes.

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