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The answer all depends on what you mean by "re-sequencing". I've seen this definition used to mean one of two things. Either using new sequence numbers in every row of the table for a particular column, or in rearranging the rows of the table for performance reasons. If the table is highly active, and you wish to change the sequence numbers of a specific column, then your best bet is to do this type of maintenance while the database is in RESTRICTED mode. This way, the application users can not cause any harm to the data while you are changing it. If you mean to rearrange the rows for performance reasons, then I suggest that you don't worry about it. A Relational Database Management System does not guarantee row order in the database. And rows can move from time to time depending on the operations against the data. I have yet to see any proven results which show that reordering the data on the physical level gives improved performance. I have seen some misguided results which on the surface appear to make this claim, but these were quickly misproven.
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This was first published in July 2002
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