Re: GSOC13 proposal - extend RETURNING syntax

W dniu 04.10.2013 02:51, Robert Haas pisze:
> Do you have a link to previous discussion on the mailing list?
Sorry, most of discussion was at IRC channel.
> I'm not positive there's enough information available
> at that stage, but if p_target_rangetblentry is populated at that
> point, you should be able to make AFTER.x translate to a Var
> referencing that range table entry.
It's not enough. Even if we know "where we are", there are more issues.
The main question is: how should we pass information about "hello, I'm
specific Var, don't evaluate me like others"? We can add two fields to
Var structure (flag - normal/before/after and no. column) - however it
needs to modify copyObject for Vars (at now it's done e.g. in
flatten_join_alias_vars_mutator for varoattno and varnoold). If
copyObject is modified, sure code in
flatten_join_alias_vars_mutator/pullup_replace_vars_callback will be
useless. I don't know if modifying pg at the low-level (changing
structure of Var and behaviour of copyObject) is good idea. Yes if the
community really want it but it needs more "votes". There is "medium"
solution: changing Var structure and do the "copy" like now (in mutator
and callback) but w/o the condition statement (for the new fields). I
think it might need to modify more places in code because of "comparing"
vars (maybe we'd need to include new fields while comparision).
Regards,
Karol Trzcionka