Re: Speed dblink using alternate libpq tuple storage

On Fri, Feb 24, 2012 at 05:46:16PM +0200, Marko Kreen wrote:
> - rename to PQrecvRow() and additionally provide PQgetRow()

I tried it and it seems to work as API - there is valid behaviour
for both sync and async connections.

Sync connection - PQgetRow() waits for data from network:

    if (!PQsendQuery(db, q))
        die(db, "PQsendQuery");
    while (1) {
        r = PQgetRow(db);
        if (!r)
            break;
        handle(r);
        PQclear(r);
    }
    r = PQgetResult(db);

Async connection - PQgetRow() does PQisBusy() loop internally,
but does not read from network:

   on read event:
    PQconsumeInput(db);
    while (1) {
        r = PQgetRow(db);
        if (!r)
            break;
        handle(r);
        PQclear(r);
    }
    if (!PQisBusy(db))
        r = PQgetResult(db);
    else
        waitForMoredata();


As it seems to simplify life for quite many potential users,
it seems worth including in libpq properly.

Attached patch is on top of v20120223 of row-processor
patch.  Only change in general code is allowing
early exit for syncronous connection, as we now have
valid use-case for it.

--
marko