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Question on index for performance

Suppose I have a column DateCreated (datetime) in a table, for this column, actually each row has different value.

Question: if index on this column improve performance? Or no need to create index for this kind of column?

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    Posted on Jul 18, 2014 at 02:38 PM

    Depends on the queries being run. The index can't help if this column isn't used to join tables or in the WHERE clause. Nor will it help if there is a better index on the table for such queries. But having it will slow the performance of inserts, updates, and deletes as ASE now has to also maintain the index entries.

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    • The leaf level of the index will have the same full key values as the original data. Higher levels of the index may contain values that are truncated (called suffix-compression) so only as much of the value is stored as is needed to navigate the tree.

      If there are no indexes then you will always get a table scan.

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