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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 Tue, 07 Feb 2012 03:11:14 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_not_for_commit_patch2_stat.txt
                DERBY_4631_not_for_commit_patch2_diff.txt

Attaching an updated patch which is still not ready for commit but it fixes two queries listed
earlier which were failing with 1st patch, 

With the query using column a+1 in the select query, I was looking for field name in ResultColumn
which would be null for an expression like a+1. Instead, I need to use exposedName which will
not be null for an expression. Instead, we internally generate a name for such columns.

With the query using order by, I found that in the new code for code generation, I need to
let Derby do what it does today for ResultColumns with VirtualColumnNode underneath. Such
a case can happen for order by query where we pull columns if needed for order by columns,

Next I plan to make the code changes less of a hack and then run the derbyall and junit suite
to see if we catch any failures. Another thing to do would be to add more RIGHT OUTER JOIN
test variations to see if the suggested code changes work fine with it. I will appreciate
any suggestion on what kind of RIGHT OUTER JOIN tests can be added to test the functionality.
                
> 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
>
>
> 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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