Michael Segel wrote:
Presumably he column would be indexed if you're doing operations like
max() on it anyway, so efficiency isn't the problem. I suspect the
problem would be what to do when two users tried to insert rows at
around the same time. The second would fail to commit the transaction
and have to try again.
Daniel
No.
First, you're still returning a value from the sequence that will cause an
exception. So you have overhead. Also you'd have a lot harder time trying
to manage the inserts. Also, you have to consider that its cheaper to get a
value from memory than it is to apply the max() function on a value from the
index.
Ah. I was making the assumption that the indexes were implemented
"properly." For instance, an index should keep a certain amount in
memory in order to have a reasonable chance of running quickly. So the
max and min should already be in-memory.
I take it that Derby doesn't do this?
Daniel
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