Arnaud Lesauvage <arnaud(dot)listes(at)codata(dot)eu> writes:
> I just came accross this trying to upgrade my server from 8.4.8 to 9.3.4 :
> SELECT substring('' FROM E'\\d');
> 8.4 : NULL
> 9.3 : ""
> Am I correct to expect NULL in this case ?
Not necessarily. \d will match any character that iswdigit() returns true
for. It looks like your new server is using a locale that considers ""
to be a digit.
regards, tom lane