Thank you for the response, If what you say is true, then I will forgo the Reorg concept, as it appears to be a waste of time.
-----Original Message----- From: Richard Sims [mailto:[EMAIL PROTECTED] Sent: Tuesday, October 21, 2003 7:44 AM To: [EMAIL PROTECTED] Subject: Re: Database fragmentation formula (was Re: Online DB Reorg) ... >Isn't this getting a little off the mark though? Last I checked, almost >every database on the planet (yes even pervasive sql) when allocating >pages/extents, left an amount of space unutilized at the end. In fact, if >you do a "reorg" in SQL server, it specifically asks how much space you want >to remain free in each page. Now why would you want that? So that when you >add a row to a table with a clustered index (ie. A primary key, where the >table is physically ordered the same as the index) the database does not >have to add an extent at the end of the space to house the new row. This >cuts down on logical fragmentation which is a far larger killer of databases >than the fragmentation that these formulas show. By these formuls, every >signle one of my SQL database is 25% fragmented (why, because every Sunday >they do online reorgs to fix their logical fragmentation). Logical >fragmentation turns large sequential reads into large random reads. ... Indeed, Michael. Distributed free space is a good thing in a random-access structure where inserts are performed. Some may believe that reorganization of a database always packs its contents closely together, yielding excellent adjacency and seek times. But the reload phase of a reorganization has to proceed according to the architecture and algorithms under which the database operates. In a B-tree type database, as the TSM db principally is, the reload insertions may result in a lot of splits and half-occupied pages. As customers have reported in ADSM-L postings, a reload may require twice as much space as their original database size. (This is summarized under topic "ADSM DATABASE STRUCTURE AND DUMPDB/LOADDB" in http://people.bu.edu/rbs/ADSM.QuickFacts .) It takes exceptional circumstance to justify doing such an unload-reload, and then the effects are typically short-lived. Richard Sims, BU