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Index Files or Indexes through a callback
The RDD can work with both physical index files (ADX files) but can also get the index information through callback methods from the running application.
In both situations the only information really used from the files or callback is:
•the index/tag name(s)
•the index expression
•the Unique flag
•the Descend flag.
No other information is needed. The physical sorting is done by the server. The RDD uses the information mentioned to generate a column list for the Create Index statement that it sends to the server, and also to generate an order by clause and where clause when seeking information.
The default behaviour of the RDD is to create ADX files. You can find the structure definition of these in the topic index file structure.
If you want to set the indexes through a callback, you need to add the table call backs IndexCallBack() and IndexTags()