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DataServer for Microsoft SQL Server
The DataServer Tutorial : Prime to ROWID identification : ROWID sub-section of MS SQL Server Conversion : Best index selection
 
Best index selection
The best index algorithm is used in the pull criteria when a primary index has not been found to support ROWID through both dictionary and DataServer methodologies that examine indexes in search of the optimal ROWID. The best index selection algorithm takes place during schema pull after all the server objects are created. Prior to Progress Version 7.3, a unique index with a single mandatory integer column was required to set RECID/ROWID. From Version 7.3 until OpenEdge Release 11.0, a single column index may be selected automatically if one or many columns exist that meet the criteria of being mandatory and unique.
The ranking protocol used to choose the first/best RECID/ROWID index is shown in the following table.
Table 51. Best index ranking criteria
Rank
Mandatory Unique Single- Component1
Integer
Date 2
Float3
V7.3 Compatible ROWID
Auto- selected ROWID
1
?
?
?
?
2
?
?
3
?
?
?
4
?
?
?
?
5
?
?
6
7
?
8
?
?

1 Automatically selectable

2 Issues sorting date fields, decreases rank

3 Issues with equality in WHERE clauses, decreases rank