Re: Adding CORRESPONDING to Set Operations
| От | Kerem Kat |
|---|---|
| Тема | Re: Adding CORRESPONDING to Set Operations |
| Дата | |
| Msg-id | CAJZSWkWHxeb5-O2k30riBrSWsvRsBg_eueVg+8QqLZzKerfQww@mail.gmail.com обсуждение исходный текст |
| Ответ на | Adding CORRESPONDING to Set Operations (Kerem Kat <keremkat@gmail.com>) |
| Список | pgsql-hackers |
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 <keremkat@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.
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