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From "Mamta A. Satoor (Updated) (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DERBY-4631) Wrong join column returned by right outer join with NATURAL or USING and territory-based collation
Date Thu, 23 Feb 2012 06:01:51 GMT

     [ https://issues.apache.org/jira/browse/DERBY-4631?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Mamta A. Satoor updated DERBY-4631:
-----------------------------------

    Attachment: DERBY_4631_patch4_diff.txt

I found the problem which was causing array index out of bound exception with the previous
patch(patch 3).

The query which was throwing the exception is as follows
INSERT INTO derby4631_t3
                       SELECT x,
                       'a'
                       FROM derby4631_t2 NATURAL RIGHT OUTER JOIN derby4631_t1;

The columns in derby4631_t3 are named x1 and y1. The source for column x1 in insert above
is join column x. In the patch, when we look to determine if the column is a join column,
I was looking at column's external name rather than it's base name. So instead of looking
for column named 'x', the earlier patch was looking for column 'x1' to see if it is a join
column. Because of that, it didn't identify join column x in the SELECT query. I have fixed
one line of code in ResultColumnList to fix the problem. So, instead of 
if (joinColumn.getName().equals(rc.getName())) {
it now checks
if (joinColumn.getName().equals(rc.name)) {

I will run the derbyall and junit suite to make sure no existing tests fail with this new
patch. I will also continue writing few more tests for JOINs.

                
> Wrong join column returned by right outer join with NATURAL or USING and territory-based
collation
> --------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-4631
>                 URL: https://issues.apache.org/jira/browse/DERBY-4631
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 10.6.1.0
>            Reporter: Knut Anders Hatlen
>            Assignee: Mamta A. Satoor
>              Labels: derby_triage10_8
>         Attachments: DERBY_4631_not_for_commit_patch1_diff.txt, DERBY_4631_not_for_commit_patch1_stat.txt,
DERBY_4631_not_for_commit_patch2_diff.txt, DERBY_4631_not_for_commit_patch2_stat.txt, DERBY_4631_patch3_diff.txt,
DERBY_4631_patch3_stat.txt, DERBY_4631_patch4_diff.txt
>
>
> SQL:2003 says that the join columns in a natural join or in a named
> columns join should be added to the select list by coalescing the
> column from the left table with the column from the right table.
> Section 7.7, <joined table>, syntax rules:
> > 1) Let TR1 be the first <table reference>, and let TR2 be the <table
> > reference> or <table factor> that is the second operand of the
> > <joined table>. Let RT1 and RT2 be the row types of TR1 and TR2,
> > respectively. Let TA and TB be the range variables of TR1 and TR2,
> > respectively. (...)
> and
> > 7) If NATURAL is specified or if a <join specification> immediately
> > containing a <named columns join> is specified, then:
> (...)
> > d) If there is at least one corresponding join column, then let SLCC
> > be a <select list> of <derived column>s of the form
> >
> > COALESCE ( TA.C, TB.C ) AS C
> >
> > for every column C that is a corresponding join column, taken in
> > order of their ordinal positions in RT1.
> For a right outer join, Derby doesn't use COALESCE(TA.C, TB.C), but
> rather just TB.C (the column in the right table) directly.
> This is in most cases OK, because COALESCE(TA.C, TB.C) = TB.C is an
> invariant in a right outer join. (Because TA.C is either NULL or equal
> to TB.C.)
> However, in a database with territory-based collation, equality
> between two values does not mean they are identical, especially now
> that the strength of the collator can be specified (DERBY-1748).
> Take for instance this join:
> ij> connect 'jdbc:derby:testdb;create=true;territory=en_US;collation=TERRITORY_BASED:SECONDARY';
> ij> create table big(x varchar(5));
> 0 rows inserted/updated/deleted
> ij> insert into big values 'A','B','C';
> 3 rows inserted/updated/deleted
> ij> create table small(x varchar(5));
> 0 rows inserted/updated/deleted
> ij> insert into small values 'b','c','d';
> 3 rows inserted/updated/deleted
> ij> select x, t1.x, t2.x, coalesce(t1.x, t2.x) from small t1 natural right outer join
big t2;
> X    |X    |X    |4    
> -----------------------
> A    |NULL |A    |A    
> B    |b    |B    |b    
> C    |c    |C    |c    
> 3 rows selected
> I believe that the expected result from the above query is that the
> first column should have the same values as the last column. That is,
> the first column should contain {'A', 'b', 'c'}, not {'A', 'B', 'C'}.

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