Emmanuel Cecchet <m...@asterdata.com> writes:
> Yes, there is a good reason. As a trigger can update the tuple value, 
> this can change the routing decision. If you have a user trigger that 
> tries to change the key value after the partition choice has been made, 
> this will lead to an integrity constraint violation which is probably 
> not what the user expects.

[ shrug... ]  Badly written user triggers can break FK constraints,
too.  We've tolerated that in the past because preventing it disables
useful capabilities.

I remain of the opinion that if you think you *have to* execute last,
you should not be writing this as a trigger; you'd be better off
embedding it lower in the system.

                        regards, tom lane

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