Search Postgresql Archives

Re: When does CLUSTER occur?

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



MSSQL uses an index to maintain the cluster.

If a record fits between it places it there, if it doesn't, it considers either moving data or adding it physically out of order (while maintaining the index)

Kind regards/met vriendelijke groet,

Serge Fonville

http://www.sergefonville.nl

Convince Microsoft!
They need to add TRUNCATE PARTITION in SQL Server
https://connect.microsoft.com/SQLServer/feedback/details/417926/truncate-partition-of-partitioned-table



2012/11/29 Mike Christensen <mike@xxxxxxxxxxxxx>

On Thu, Nov 29, 2012 at 10:28 AM, Shaun Thomas <sthomas@xxxxxxxxxxxxxxxx> 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..


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Postgresql Jobs]     [Postgresql Admin]     [Postgresql Performance]     [Linux Clusters]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Postgresql & PHP]     [Yosemite]
  Powered by Linux