From: erik.lennart.jonsson@gmail.com   
      
   On 2011-11-29 23:45, Erland Sommarskog wrote:   
   [...]   
   >   
   > I don't know about DB2, but I know that in Oracle, heaps are the norm,   
   > and index-organised tables is something you use rarely. In SQL Server,   
   > it is the other way around. The clustered index is the normal thing,   
   > and heaps is something you only use sometimes. Except in SQL Azure,   
   > where heaps are not even supported. All mindsets in SQL Server is   
   > geared on clustered indexes, and you better know what you are doing if   
   > use a heap.   
   >   
      
   Hi Erland, reading the links provided by Bob made me realize that that   
   are some essential differences between db2 and sql-server (when it comes   
   to clustering indexes anyhow). If I got it right, the leaf pages in a   
   clustered index in sql-server is the data pages. In db2 leaf pages   
   contains a pointer to the data page just like any other index.   
      
   In db2 the main focus is how queries may benefit from the clustering   
   index (reduce i/o and sort), and clustering indexes is therefor not   
   added until one is knows what the typical queries are. This may of   
   course be known at design time, but is often not discovered until later.   
      
   Where the clustering strategy used in my example would have been   
   absolutely braindead in db2, it makes a whole lot more sense in   
   sql-server (even if there seems to be some controversy of what strategy   
   to choose).   
      
   Looking at other constructions in the datamodel, I'll bet a dollar or   
   two on your auto pilot hyphothesis.   
      
      
   Cheers   
   /Lennart   
      
      
   [...]   
      
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