I am curious that what is differences between ArcSDE 9.3 and ArcSDE 10?
Is there ArcSDE 10 to use it?
Or ArcSDE 10 is coming with ArcGIS for Servers?
Can anyone explain me?
Edit : Another helpful answer to this question is here ; ArcSDE performance and table changes on upgrade from 9.3 to 10.1?
To learn what was new in the ArcSDE component of ArcGIS Server 10.0 I recommend reviewing What's new for geodatabases in ArcGIS 10 where just one example of a change since 9.3 is:
Geodatabase system tables have been consolidated
The geodatabase schema has been restructured for the ArcGIS 10 release, consolidating the information previously stored in the geodatabase system tables into six tables. This is done partly by using XML columns to store information related to the data in the geodatabase.
All new and upgraded file, personal, and ArcSDE geodatabases will have the new geodatabase schema.
To implement this new schema in an ArcSDE geodatabase, the database must be able to use XML columns. Additionally, existing ArcSDE geodatabases must be upgraded using the new Upgrade Geodatabase geoprocessing tool or Python script instead of the Post Installation wizard or the sdesetup command.
Your question seems more philosophical than technical. In truth, nothing of significance changed in ArcSDE between ArcGIS 9.3 and 10.0. The ArcGIS geodatabase metadata was completely redesigned, with an increased emphasis on Direct Connect, but that just furthers the transition of ArcSDE from product to technology started back at ArcGIS 9.2. You're also working at a serious disadvantage by upgrading so late from 9.x to 10.0, since ArcSDE itself is at the cusp of disappearing completely at ArcGIS 10.3.
If you want to get ahead of the curve, you can start by erasing "ArcSDE" from your vocabulary and replacing it with "ArcGIS" or "enterprise geodatabase". That would morph the question into: "What are the differences in enterprise geodatabase implementation between ArcGIS 9.3 and 10.0?", for which you already have an accepted answer.
