Mailing-List: contact derby-dev-help@db.apache.org; run by ezmlm
Precedence: bulk
Reply-To: <derby-dev@db.apache.org>
Message-ID: <478067933.1242841425635.JavaMail.jira@brutus>
Date: Wed, 20 May 2009 10:43:45 -0700 (PDT)
From: "Mamta A. Satoor (JIRA)" <jira@apache.org>
To: derby-dev@db.apache.org
Subject: [jira] Commented: (DERBY-3926) Incorrect ORDER BY caused by index
In-Reply-To: <587695671.1225270724527.JavaMail.jira@brutus>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit


    [ https://issues.apache.org/jira/browse/DERBY-3926?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12711252#action_12711252 ] 

Mamta A. Satoor commented on DERBY-3926:
----------------------------------------

Mike asked "Do you know how the current code determines that sort can be avoided in the one remaining 
case? Does it do something special with the equality condition? " I do not know how the code knows about avoiding the sort in case of following query. I will spend some time understanding the code path.
select * from --DERBY-PROPERTIES joinOrder=FIXED 
TENKTUP1 -- DERBY-PROPERTIES index=TK1UNIQUE1 
, TENKTUP2 -- DERBY-PROPERTIES index=TK2UNIQUE1 
where TENKTUP1.unique1 = TENKTUP2.unique1 
order by TENKTUP1.unique1, TENKTUP2.unique1; 

> Incorrect ORDER BY caused by index
> ----------------------------------
>
>                 Key: DERBY-3926
>                 URL: https://issues.apache.org/jira/browse/DERBY-3926
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 10.1.3.3, 10.2.3.0, 10.3.3.1, 10.4.2.0
>            Reporter: Tars Joris
>            Assignee: Mamta A. Satoor
>         Attachments: d3926_repro.sql, derby-reproduce.zip, DERBY3926_notforcheckin_patch1_051109_diff.txt, DERBY3926_notforcheckin_patch1_051109_stat.txt, DERBY3926_notforcheckin_patch2_051109_diff.txt, DERBY3926_patch3_051509_diff.txt, DERBY3926_patch3_051509_stat.txt, DERBY3926_patch4_051519_diff.txt, DERBY3926_patch4_051519_stat.txt, script3.sql, script3WithUserFriendlyIndexNames.sql, test-script.zip
>
>
> I think I found a bug in Derby that is triggered by an index on a large column: VARCHAR(1024). I know it  is generally not a good idea to have an index on such a large column.
> I have a table (table2) with a column "value", my query orders on this column but the result is not sorted. It is sorted if I remove the index on that column.
> The output of the attached script is as follows (results should be ordered on the middle column):
> ID                  |VALUE        |VALUE
> ----------------------------------------------
> 2147483653          |000002       |21857
> 2147483654          |000003       |21857
> 4294967297          |000001       |21857
> While I would expect:
> ID                  |VALUE        |VALUE
> ----------------------------------------------
> 4294967297          |000001       |21857
> 2147483653          |000002       |21857
> 2147483654          |000003       |21857
> This is the definition:
> CREATE TABLE table1 (id BIGINT NOT NULL, PRIMARY KEY(id));
> CREATE INDEX key1 ON table1(id);
> CREATE TABLE table2 (id BIGINT NOT NULL, name VARCHAR(40) NOT NULL, value VARCHAR(1024), PRIMARY KEY(id, name));
> CREATE UNIQUE INDEX key2 ON table2(id, name);
> CREATE INDEX key3 ON table2(value);
> This is the query:
> SELECT table1.id, m0.value, m1.value
> FROM table1, table2 m0, table2 m1
> WHERE table1.id=m0.id
> AND m0.name='PageSequenceId'
> AND table1.id=m1.id
> AND m1.name='PostComponentId'
> AND m1.value='21857'
> ORDER BY m0.value;
> The bug can be reproduced by just executing the attached script with the ij-tool.
> Note that the result of the query becomes correct when enough data is changed. This prevented me from creating a smaller example.
> See the attached file "derby-reproduce.zip" for sysinfo, derby.log and script.sql.
> Michael Segel pointed out:
> "It looks like its hitting the index ordering on id,name from table 2 and is ignoring the order by clause."

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.