I am working on a process that will be inserting tens of million rows
and need this to be as quick as possible.
The catch is that for each row I could potentially insert, I need to
look and see if the relationship is already there to prevent
multiple entries. Currently I am doing a SELECT before doing the
INSERT, but I recognize the speed penalty in doing to operations. I
wonder if there is some way I can say "insert this record, only if it
doesn't exist already". To see if it exists, I would need to compare
3 fields instead of just enforcing a primary key.
Even if this could be a small increase per record, even a few percent
faster compounded over the whole load could be a significant reduction.
Thanks for any ideas you might have.
-Dan
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