Re: [HACKERS] New CORRESPONDING clause design

Hi

I am sending a review of this interesting feature.

I found following issues, questions:

1. unclosed tags <optional> in documentation 

2. bad name "changeTargetEntry" - should be makeTargetEntry?

3. Why you removed lot of asserts in prepunion.c? These asserts should be valid still 

4. make_coresponding_target has wrong formatting

5. error "%s queries with a CORRESPONDING clause must have at least one column with the same name" has wrong formatting, you can show position

6. previous issue is repeated - look on formatting ereport function, please, you can use DETAIL and HINT fields

7. corresponding clause should to contain column list (I am looking to ANSI/SQL 99)  - you are using expr_list, what has not sense and probably it has impact on all implementation.

8. typo orderCorrespondingLsit(List *targetlist)

9. I miss more tests for CORRESPONDING BY

10. if I understand to this feature, this query should to work

postgres=# SELECT 1 a, 2 b, 3 c UNION CORRESPONDING BY (c,b) SELECT 4 a, 5 b, 6 c, 8 d;
ERROR:  each UNION query must have the same number of columns
LINE 1: ...1 a, 2 b, 3 c UNION CORRESPONDING BY (c,b) SELECT 4 a, 5 b, ...

postgres=# create table t1(a int, b int, c int);
CREATE TABLE
Time: 63,260 ms
postgres=# create table t2(a int, b int);
CREATE TABLE
Time: 57,120 ms
postgres=# select * from t1 union corresponding select * from t2;
ERROR:  each UNION query must have the same number of columns
LINE 1: select * from t1 union corresponding select * from t2;

If it is your first patch to Postgres, then it is perfect work!

The @7 is probably most significant - I dislike a expression list there. name_list should be better there.

Regards

Pavel