Re: vacuum, performance, and MVCC

Lukas Smith <smith@pooteeweet.org> writes:
> Jochem van Dieten wrote:
>> make the session handler smarter? And if you can't do that, put some
>> logic in the session table that turns an update without changes into a
>> no-op?

> err isnt that one the job of the database?

No.  That idea has been suggested and rejected before.  Detecting that
an UPDATE is a no-op would require a significant number of cycles, and
in most applications, most or all of the time those cycles would be
wasted effort.  If you have a need for this behavior, you can attach a
BEFORE UPDATE trigger to a table that checks for all-fields-the-same and
suppresses the update.  I don't think that should be automatic though.
        regards, tom lane