| From: | Mike Christensen <mike(at)kitchenpc(dot)com> |
|---|---|
| To: | sthomas(at)optionshouse(dot)com |
| Cc: | Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, "Schnabel, Robert D(dot)" <schnabelr(at)missouri(dot)edu>, "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: When does CLUSTER occur? |
| Date: | 2012-11-29 18:34:56 |
| Message-ID: | CABs1bs19Kbf-hn_TOkgw-wsSjc-K1xjGYS6YFjRqwE94WsUbaQ@mail.gmail.com |
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| Lists: | pgsql-general |
On Thu, Nov 29, 2012 at 10:28 AM, Shaun Thomas <sthomas(at)optionshouse(dot)com>wrote:
> On 11/29/2012 12:20 PM, Jeff Janes wrote:
>
> It would maintain an imperfect clustering, but still much better than
>> current behavior.
>>
>
> I thought about that, too. The "imperfect clustering" made me erase
> everything I'd written. If the clustering is imperfect, it's not really
> clustering. It would mean less random reads to restart the seek chain
> though, so it would be a perceptible gain. But it's still not real
> clustering until the order is maintained indefinitely.
>
> So far as I know, that simply can't be done with MVCC. Especially on an
> insert-only table that's clustered on a column unrelated to insert order.
>
>
How is this implemented in MS SQL then? Obviously, MS SQL supports real
clustering and has MVCC..
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