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You should be able to enable logging for debugging purposes, however the question of whether to log every SELECT depends on how much this data is worth to you - are you prepared to spend the money on a server powerful enough to log this data and the price of a backup strategy for this data. Furthermore, there's little point in logging everything if you ...


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If your system gets pounded with hundreds of queries every second and you have a storage constraint, it does not make sense to log every query.Assume the maximum allowed response time at user-end is x seconds. Other tiers plus network latency may take upto y seconds. So the maximum permissible time at db tier is x-y seconds. Any query that takes more than ...


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The key is actually AE. The proof is simple, a key for definition is a minimal set of attributes whose closure contains all the attributes of the table. If you calculate the closure of A with respect to the given functional dependencies you will find: A+ = {ABCD} that does not contain the attribute E. So A is not a key, and E must be present in any key of ...


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Now that I'm not using my phone to look at this question; I see the reason your construction "works". Since you are using nullable fields for the foreign keys, you can in fact construct a system that works correctly the way you envision it. In order to insert rows into the Accounts table you need to have a row present in the Contacts table unless you ...


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No, it's not acceptable to have circular foreign key references. Not only because it would be impossible to insert data without constantly dropping and recreating the constraint. but because it is a fundamentally flawed model of any and every domain I can think of. In your example I cannot think of any domain in which the relationship between Account and ...



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