Is it feasible to implement the CORRESPONDING [BY (expr_list)] statement in set operations by the following changes:
i) In analyze.c:transformSetOperationStmt after parsing left and right queries as subnodes to a set operation tree, a) CORRESPONDING: Find matching column targets from both statements, eliminate unmatching targets and proceed. b) CORRESPONDING BY (expr_list): Verify expr_list columns exist in both select statements. Eliminate unmatched column names to expr_list and proceed. ii) Instead of elimination set TargetEntry->resjunk = true for unwanted output columns. Thank you for your attention, Any comments are welcome. Kerem KAT On Sun, Sep 18, 2011 at 12:39, Kerem Kat <kerem...@gmail.com> wrote: > Hello, > > I am new to postgresql code, I would like to start implementing easyish > TODO items. I have read most of the development guidelines, faqs, articles > by Greg Smith (Hacking Postgres with UDFs, Adding WHEN to triggers). > > The item I would like to implement is adding CORRESPONDING [BY > (col1[,col2,...]])] to INTERSECT and EXCEPT operators. > > Can anyone comment on how much effort this item needs? > > > regards, kerem kat. >