How Indexes are Used by ORDER BY Clauses
Advantage SQL Engine
How Indexes are Used by ORDER BY Clauses Advantage SQL Engine |
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How Indexes are Used by ORDER BY Clauses Advantage SQL Engine |
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Existing indexes may be used to sort live cursors when the index expression matches the expression in the ORDER BY clause. For example, "select * from employee order by lastname" will result in a live cursor that will use an index built on lastname if one exists. If such an index does not exist, a temporary one will be created by the server and deleted when the cursor is closed. If a specific query is common, it probably makes sense to create a permanent index on the field or fields used in the ORDER BY clause.