For a primary key of an integral type, why is it important to avoid gaps ?
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by Jacques René Mesrine
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Published on 2010-03-29T02:27:46Z
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I am generating a surrogate key for a table & due to my hi/lo algorithm, everytime you reboot/restart the machine, gaps may appear.
T1: current hi = 10000000
(sequence being dished out .. 1 to 100)
Assume that current sequence is 10000050
T2: restart system.
T3: System gives out the next_hi as 10000100
(sequence being dished out now ranges from 101 to 200)
T4: Next request for a key returns 100001001
From a primary key or indexing internals perspective, why is it important that there be no gaps in the sequences ? I'm asking this for a deeper understanding of mysql specifically.
Thanks
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