Hello new hstore has a very nice interface for record field iteration
http://okbob.blogspot.com/2009/10/dynamic-access-to-record-fields-in.html Regards Pavel Stehule 2009/11/13 Florian G. Pflug <f...@phlo.org>: > Hi > > I'm currently working on a project where we need to build a global cache > table containing all values of certain types found in any of the other > tables. Currently, a seperate insert, update and delete (plpgsql) > trigger function exists for each table in the database which is > auto-generated by a (plpgsql) function which queries the system catalogs > to find all fields with a certain type, and then generates the > appropriate plpgsql function using EXECUTE '...'. > > I'd like to replace this function-generating function by a generic > trigger function that works for all tables. Due to the lack of any way > to inspect the *structure* of a record type, however, I'd have to use a > C language function for that, which induces quite some maintenance > headaches (especially if deployed on windows). > > I'm therefore thinking about implementing the following generate-purpose > inspection functions for row types > > record_length(record) returns smallint > Returns the number of fields in the given record. > > record_names(record) returns name[] > Returns the names of the record's fields. Array will contain NULLs > if one or more fields are unnamed. > > record_types(record) returns regtype[]; > Returns the OIDs of the record's types. Array won't contain NULLs > > record_value(record, name, anyelement) returns anyelement > Returns the value of a certain (named) field. The type of the third > argument defines the return type (its value is ignored). The > field's value is cast to that type if possible, otherwise an > error is raised. > > record_value(record, smallint, anyelement) returns anyelement > Returns the value of the field at the given position. > > record_values(record, regtype, anyelement) returns anyarray > Returns an array of all values of all fields with the given type or > whose type is a domain over the given type. No casting is done. > > Any comment/critique is appreciated. > > Would anyone else find those functions useful? > > best regards, > Florian Pflug > > -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
