January 28, 2013 at 12:07 am
My personal opinion is that if you're not going to persist a calculated column, write a derived table or view, instead. That way, no one can screw up and actually make queries that even try to use it effeciently. 😛
--Jeff Moden
January 28, 2013 at 9:22 am
Jeff Moden (1/28/2013)
My personal opinion is that if you're not going to persist a calculated column, write a derived table or view, instead. That way, no one can screw up and actually make queries that even try to use it effeciently. 😛
Typically the overhead to materialize the computed column (cc) at run time trivial. If it is, a cc has a lot of advantages, so I suggest using it as intended.
A derived table risks differing definitions in multiple queries.
A view forces people to use different queries to access the data depending on whether they need a certain cc or not. If a query needs that cc added, you have to rewrite the query just because of that.
SQL DBA,SQL Server MVP(07, 08, 09) "Money can't buy you happiness." Maybe so, but it can make your unhappiness a LOT more comfortable!
January 28, 2013 at 5:06 pm
ScottPletcher (1/28/2013)
Jeff Moden (1/28/2013)
My personal opinion is that if you're not going to persist a calculated column, write a derived table or view, instead. That way, no one can screw up and actually make queries that even try to use it effeciently. 😛Typically the overhead to materialize the computed column (cc) at run time trivial. If it is, a cc has a lot of advantages, so I suggest using it as intended.
A derived table risks differing definitions in multiple queries.
A view forces people to use different queries to access the data depending on whether they need a certain cc or not. If a query needs that cc added, you have to rewrite the query just because of that.
Sorry Scott... I meant to put out the bright orange barrels, cones, and flags that warned people that sarcasm was "ON". Go back and read it again. It was dripping in sarcasm in support of the use of CC especially persisted CC. 😉
I'll try to give better warnings in the future.
--Jeff Moden
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