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Posted by Erland Sommarskog on 06/11/06 08:49
(wackyphill@yahoo.com) writes:
> I understand your point Erland, but these Primary keys were created w/o
> specifying that they should be non-clustered, so I'm certain they are.
You can always use sp_helpindex to find out.
> Why is it that w/o a clustered index defragmentation on non-clustered
> indexes can't occur, or did I misunderstand the previous poster?
I don't recall exactly what he said, but you can't defragment the data
pages without a clustering index. The NC indexes are defragmentable
nevertheless.
> You are correct that these tables currently are small by most people's
> standards. I'm guessing that the largest one has < 1000 records. Is it
> mentioned somewhere in SQL books on-line about free space looking lile
> fragmentaion, that I can read up on?
Let me put it this way: with tables of that size, there's usually not
much reason to worry about fragementation anyway.
Fragmentation matters when it results in data being spread out on
many extra pages. Say that you have a table with 1 GB of data. If
the data pages are only 50% full, the server needs to read 2 GB of
disk to scan all data. This can affect the performance of the system.
Whether this is spelt out in clear in Books Online, I don't know. But
you can read about the physical architecture starting on
ms-help://MS.SQLCC.v9/MS.SQLSVR.v9.en/udb9/html/33572c3b-343d-45aa-bb42-1d31423ae5cc.htm.
--
Erland Sommarskog, SQL Server MVP, esquel@sommarskog.se
Books Online for SQL Server 2005 at
http://www.microsoft.com/technet/prodtechnol/sql/2005/downloads/books.mspx
Books Online for SQL Server 2000 at
http://www.microsoft.com/sql/prodinfo/previousversions/books.mspx
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