Re: PostgreSQL win32 fragmentation issue

On Sun, Dec 03, 2006 at 11:54:05AM +0100, Magnus Hagander wrote:
> Yes, they definitly do. That's why for exapmle SQLServer provides the
> commands "DBCC CHECKCONTIG" and "DBCC INDEXDEFRAG". Along with comments
> like this:
>
> "DBCC SHOWCONTIG determines whether the table is heavily fragmented.
> Table fragmentation occurs through the process of data modifications
> (INSERT, UPDATE, and DELETE statements) made against the table. Because
> these modifications are not ordinarily distributed equally among the
> rows of the table, the fullness of each page can vary over time. For
> queries that scan part or all of a table, such table fragmentation can
> cause additional page reads. This hinders parallel scanning of data."

But that's measuring something else I think. That's not looking at how
the pages are physically mapped on disk, but at how tuples are spread
across pages.. Maybe in sqlserver tuples can span pages?

That's not a kind of fragmentation relevent to postgresql. This is what
the FSM is for.

Have a nice day,
--
Martijn van Oosterhout   <kleptog@svana.org>   http://svana.org/kleptog/
> From each according to his ability. To each according to his ability to litigate.