Hannes Erven wrote : > Hi folks, > > > On 2013-03-22 13:32, Bertrand Janin wrote: > > UPDATE demo > > SET value = value > > WHERE id = 1; > > > On 2013-03-22 14:55, Tom Lane wrote: > > > >It's not *necessary* to do so. However, avoiding it would require > >sitting there and comparing the old and new tuples, > > > But in this case, no tuples would need to be compared: just by > looking at the query is becomes clear that it is a no-op. > Isn't this something the planner is or could be aware of? > > Betrand, out of curiosity: is this a synthentic test case or do you > really have an application that generates queries like this? I used the value=value to emphasize the example, in my use case it would be value='whatever is already there'. Tom is right, this would be an optimization for a corner case, I noticed this when running a generated script for a batch update that wasn't given a ton of attention. The BEFORE UPDATE trigger will work great. -b -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
