Hi,

> While the opportunities for parallelism for queries are sparse, there
> are all sorts of interesting things that I'm doing in Falcon for the
> update side. Updates in work this way:

With Updates you meant Update/Delete/Insert i guess?

> 1. The client thread performs updates in memory (records and indexes)
> 2. Blobs, however, are written to page images in the cache. When a
> blob is complete, a separate thread, the page writer, starts
> writing it.
> 3. At commit time, the updates (records and indexes) are written to a
> serial log. When the page writer is done writing all blobs, a
> commit record is written to the serial log, and the transaction is
> considered committed.
> 4. Post commit, another thread, the gopher (go fer this, go fer that)
> copies stuff (records and index updates) from the serial log to
> page images.
> 5. Yet another thread, the system scheduler, fires of periodically to
> checkpoint the page cache to the disk.

> So data from a single transaction passes through a client thread, the
> page writer, the gopher, and the scheduler. Letting updates run
> unblocked in memory until commit, then waiting only for the basic bits
> to hit the oxide, letting other threads migrate data to disk later leads
> to incredible update performance.

If i understand correctly the gopher thread (4) should never run simultaneously with "page cache to
disk" scheduler (5), because pages dependend on their precedence to other pages could be written
wrong.

Regards,
Arno Brinkman
ABVisie

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