Update:

Update:

< * Allow DEFERRABLE UNIQUE constraints?
> * Allow DEFERRABLE and end-of-statement UNIQUE constraints?
>
>   This would allow UPDATE tab SET col = col + 1 to work if col has
>   a unique index.  Currently, uniqueness checks are done while the
>   command is being executed, rather than at the end of the statement
>   or transaction.
>