ROWID vs Clustered Key

  • Hi All,

    Performance wise is there any difference using (by non-clustered index) ROW ID(for heap) vs Clustered Key id?

    Thank You

  • I believe the answer is Yes there is a performance difference.

    The non-clustered index on a HEAP must find the page using the ROWID then find the row data on the page. Clustered table the non-clustered index points to the exact row in the clustered index by the clustering key. The linked-list nature of the B-tree also increases the probability that related rows will be in memory.

  • Correct me if i am wrong:

    Using Clustering key sql server retrives data from memory vs

    using Rowid from disk

  • Depends if the data page needed for the query is in memory (cached) or not.

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