See the discussion of Custom-Scan API. https://commitfest.postgresql.org/action/patch_view?id=1282
I believe my third patch is what you really want to do... > This rewritten query would be handled by the FDW table that I previously > added to the catalog. > > The reason I want this new hook is that I don't want tableA and tableB to be > in the catalog. > I'd like to see why you wants the pseudo table "fdw_tableA_tableB" to be in the catalog, instead of the "tableA" and "tableB". In addition, parser shall raise an error if referenced columns (as a part of "tableA" or "tableB") are not in-catalog because of name lookup error. Thanks, 2014-02-13 19:01 GMT+09:00 David Beck <db...@starschema.net>: > Hello Hackers, > > I work on a foreign data wrapper for a legacy system. I generally find the > hook system very useful and flexible way to extend Postgres. > The post parse analyze hook almost fits what I need, but I have a few use > cases where I would need to tap right into the parsed queries but before any > catalog based validation is done. > Please find the attached trivial patch for this new hook. > > One of the use cases I have is this: > > I have table like data structures in the source system for the FDW I work on. > These tables are sometimes too big and the source system is able to filter > and join them with limitations, thus it is not optimal to transfer the data > to Postgres. > At the same time I want the users to think in terms of the original tables. > > The idea is to rewrite the SQL queries like this: > > "SELECT * FROM tableA a, tableB b WHERE a.id=b.id AND a.col1=1234 AND > b.col2=987" > > to: > > "SELECT * FROM fdw_tableA_tableB ab WHERE ab.col1=1234 AND ab.col2=987" > > > This rewritten query would be handled by the FDW table that I previously > added to the catalog. > > The reason I want this new hook is that I don't want tableA and tableB to be > in the catalog. > > Looking forward to hear your thoughts, opinions, comments. > > Best regards, David > > > > > > -- > Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-hackers > -- KaiGai Kohei <kai...@kaigai.gr.jp> -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
