From: | Demian Lessa <demian(at)lessa(dot)org> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | Constraint validation |
Date: | 2007-03-02 00:42:11 |
Message-ID: | 45E772E3.4060007@lessa.org |
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Thread: | |
Lists: | pgsql-general |
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Hi,
After browsing the source, and running some experiments, it seems like
PostgreSQL blindly verifies all CHECK constraints for an update, even if
the update COULDN'T possibly be violated by the specified update (for
instance
UPDATE table SET field3=value WHERE condition
and there is no CHECK constraint on field3. I compared my observations
with what I saw by running the same experiments in Oracle, and they seem
to verify constraints selectively.
Two questions: is there a reason for this behavior in PostgreSQL? and,
does this also hold for other constraints such as PRIMARY KEYs, UNIQUEs,
and FOREIGN KEYs?
Thanks,
Demian
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