Articles tagged

05 September 2016
05 September 2016

Massive Deletes – Part 4

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In the previous installment of this series I produced some figures highlighting the main differences between doing a large delete by tablescan and doing a large delete by index range scan. Depending on the data patterns involved the correct choice of strategy could make a significant difference to the number of random I/Os, the volume of redo generated, and t… Read more
05 April 2016
05 April 2016

Massive Deletes – Part 3

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In the previous installment of this series we looked at methods for seeing the pattern of the changes that would appear in a table and its indexes after a large delete. In this installment we move on to the workload implied by different patterns, then think about strategies or, indeed, the need for strategies for reducing that workload at t… Read more
17 February 2016
17 February 2016

Massive Deletes – Part 2

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In Part 1 of this short series I provided an informal description of a couple of scenarios where we might do a large-scale delete from a table. Without a concrete example though, it can be hard to imagine how the nature of the data deleted and the access paths available could affect the impact a large delete operation could hav… Read more
29 January 2016
29 January 2016

Massive Deletes – Part1

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In a recent article about dropping columns from a table I left hanging the question of what you might do after you have dropped the column, because dropping a column is really nothing more than a special case of the “massive delete”. In this article, then, I’m going to lay the groundwork for how we ought to think around t… Read more