2009/5/24 Tom Lane <t...@sss.pgh.pa.us>: > Pavel Stehule <pavel.steh...@gmail.com> writes: >> ==Steps== >> 1. add hook to analyser (transform stage) to substitute unknown >> columnref by param - when analyser detect unknown columnref, then call >> callback, that returns possible para node or NULL (when external >> environment doesn't have a variable). Returned param should be typed >> or unknown (for polymorphic params). > > IMHO the hook definition should support both the case of external > variables taking precedence over query variables and vice versa. > I don't think the core parser should be forcing that decision. In any > case we'd probably need both options for plpgsql, so as to be able to > support both traditional and Oracle-compatible behavior.
good idea > > I'd be inclined to do that by letting the hook function interpose > itself between the parser and the regular transformColumnRef processing, > so that it can call the regular transformColumnRef processing either > before or after doing its external lookups. Giving it control only > after the regular processing fails would mean there's no way to let > external variables take precedence. > ok >> 2. add special modes to sql parser: > > None of those seem like a good idea to me. The only part that seems > useful is warning about conflicts between external variables and query > variables. That can be implemented by the hook function itself, if we > define the hook behavior as above. > there is minimal one necessary - for polymorphic variables, we know name, but we don't know type. And without types, we can't to transform correctly functions. regards Pavel Stehule > regards, tom lane > -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
