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Re: Locking to restrict rowcounts.

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Richard Huxton wrote:
Glen Parker wrote:
Richard Huxton wrote:

#3 won't work unless the other transactions have all committed by the time you do the check. It is guaranteed to fail at some point.

If it's in an AFTER INSERT/UPDATE trigger then whatever transaction takes you beyond 10 rows you will always get a failure. If you get a lot of insert/delete pairings then you could spend a lot of time counting rows, but that's all.


I still don't think it will work. Two concurrent transactions could still screw the data up.

Before: 9 rows.
Tx 1: See 9 rows, issue insert, see 10 rows.
Tx 2: See 9 rows, issue insert, see 10 rows.
After: 11 rows.

-Glen


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