2010/1/28 Hitoshi Harada <umi.tan...@gmail.com>: > 2010/1/29 Pavel Stehule <pavel.steh...@gmail.com>: >> 2010/1/28 Robert Haas <robertmh...@gmail.com>: >>> On Thu, Jan 28, 2010 at 9:01 AM, Pavel Stehule <pavel.steh...@gmail.com> >>> wrote: >>>> simplest could not be a best. There have to be only a const >>>> expression. But we have not possibility to check it in pg. >>> >>> Well... that's an entirely arbitrary limitation. I admit that it >>> doesn't seem likely that someone would want to have a variable >>> delimiter, but putting extra effort and code complexity into >>> preventing it seems pointless. >> >> It is only a few lines with zero complexity. >> >> The main issue of Takahiro proposal is "unclean" behave. >> >> we can have a content >> >> c1 c2 >> ----------- >> c11, c12, >> c21, c22 >> >> and result of string_agg(c1, c2) >> >> have to be ?? c11 c12 c21 or c11 c22 c21 ?? What if some content of c2 >> will be NULL ?? I checked oracle. Oracle doesn't allow variable as >> delimiter. We can't check it. But we can fix first value and using it >> as constant. > > What about get_fn_expr_arg_stable() to check if the argument is stable > during aggregate?
I newer know so this function exists. Now we can a) check and allow only stable params b) when second parameter is stable, then store it and use it as constant. I prefer a) Pavel > > Regards, > > > -- > Hitoshi Harada > -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
