Re: tackling full page writes

On Wed, May 25, 2011 at 1:06 PM, Greg Smith <greg@2ndquadrant.com> wrote:
> On 05/24/2011 04:34 PM, Robert Haas wrote:
>>
>> we could name this feature "partial full page writes" and enable it
>> either with a setting of full_page_writes=partial
>
> +1 to overloading the initial name, but only if the parameter is named
> 'maybe', 'sometimes', or 'perhaps'.

Perfect!

> I've been looking into a similar refactoring of the names here, where we
> bundle all of these speed over safety things (fsync, full_page_writes, etc.)
> into one control so they're easier to turn off at once.  Not sure if it
> should be named "web_scale" or "do_you_feel_lucky_punk".

Actually, I suggested that same idea to you, or someone, a while back,
only I was serious.  crash_safety=off.  I never got around to fleshing
out the details, though.

>> 3. Going a bit further, Greg proposed the idea of ripping out our
>> current WAL infrastructure altogether and instead just having one WAL
>> record that says "these byte ranges on this page changed to have these
>> new contents".
>
> The main thing that makes this idea particularly interesting to me, over the
> other two, is that it might translate well into the idea of using
> sync_file_range to aim for a finer fsync call on Linux than is currently
> possible.

Hmm, maybe.  But it's possible that the dirty blocks are the first and
last ones in the file.

--
Robert Haas
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